MX-E-01: US–Mexico Migration Cooperation — From Remain in Mexico to CBP One to Plan Frontera Norte (2018–2025)

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Version Date: 2026-05-16

Document Outline

Key Takeaways (10 substantial bullets)
The Pre-2018 Baseline — Bracero, IRCA, IIRIRA, Plan Mérida, and Programa Frontera Sur
The 2018 Caravan Shock and the AMLO Inheritance — From Tapachula to Tijuana
The January 2019 Migrant Protection Protocols and the May–June 2019 Tariff Negotiation (Ebrard–Mnuchin)
The Mexican Enforcement Turn — The Guardia Nacional, the Southern Border, and the Guillén Resignation
The March 2020 Title 42 Public Health Order and the COVID-Era Architecture
The Biden Transition, MPP Rescission Litigation, and the Biden v. Texas Decision (2021–2022)
The 12 January 2023 CBP One Launch and the 11 May 2023 Title 42 Termination
The 27 March 2023 Ciudad Juárez INM Detention-Centre Fire and the Garduño Indictment
The 2023–2024 Mixed-Composition Flows — Venezuelans, Cubans, Haitians, and Tren de Aragua
The October 2024 Sheinbaum Inauguration, the November Tariff Threat, and the December Plan Frontera Norte Deployment
The 20 January 2025 Trump-2 Executive-Order Cascade and the CBP One Shutdown
The 1 February 2025 IEEPA Tariff Imposition, the 3 February 30-Day Pause, and the 10,000-Troop Framework
The 15 March 2025 Alien Enemies Act Invocation and the CECOT El Salvador Transfers
The Mexican Consular Network Response, Programa Paisano, and Dual-Citizenship Promotion
Remittances 2018–2025 — The $63 Billion Cushion and the Sectoral Geography of Dependence
The May 2025 Migration-and-Fentanyl Cooperation Framework — Operational Architecture
The Three-Account Assessment — Sheinbaum-Morena Sovereignty Framing, Trump-2 Enforcement Framing, and the Structural Reading
Conclusion — Forward View on Asymmetric Border Cooperation under Interdependence

1. Key Takeaways

US–Mexico migration cooperation between 2018 and 2025 underwent four distinct architectural shifts that together constitute a single inherited-and-renegotiated system: the first Trump administration's Migrant Protection Protocols ("Remain in Mexico", launched 24 January 2019 and expanded after the 7 June 2019 Ebrard–Pompeo Joint Declaration that ended a five-week tariff-threat episode); the March 2020 Title 42 CDC public-health expulsion order that converted the southern border into a de facto asylum-suspension regime under COVID-19; the Biden-era CBP One mobile-application architecture (launched 12 January 2023, asylum-appointment functionality 5 May 2023, ~1,450 daily appointments at eight ports of entry) paired with the 11 May 2023 Title 42 termination; and the Sheinbaum-Trump-2 Plan Frontera Norte / Alien Enemies Act / IEEPA-tariff architecture across November 2024 to May 2025. Each shift was preceded by a coercive US lever — tariff threat 2019, COVID emergency 2020, court-ordered Title 42 rescission 2022–23, renewed tariff threat 2024–25 — and each was operationalised by Mexico through formal protest, Estrada-Doctrine framing, and substantive operational accommodation. The pattern reveals the structural asymmetry: the United States legislates, executes, or litigates a change; Mexico absorbs the operational consequences, negotiates cooperation boundaries, and seeks to extract value (tariff suspension, investment commitments) in exchange.
The 24 January 2019 launch of the Migrant Protection Protocols in San Ysidro / Tijuana, formalised under Section 235(b)(2)(C) of the Immigration and Nationality Act and operationalised through DHS Secretary Kirstjen Nielsen's policy guidance, returned approximately 71,000 non-Mexican asylum seekers to Mexican territory to await US immigration-court adjudication between January 2019 and the end of January 2021. The principal return points were Tijuana (Baja California), Mexicali, Ciudad Juárez (Chihuahua), Nuevo Laredo (Tamaulipas), Matamoros (Tamaulipas), and Piedras Negras (Coahuila). The Matamoros tent encampment, which at its peak housed approximately 2,500 returnees in conditions documented by Human Rights First, MSF, and the Strauss Center for International Security and Law as among the most precarious in the Western Hemisphere, became the most visible symbol of the policy. The Mexican government — initially under Foreign Secretary Marcelo Ebrard, INM Commissioner Tonatiuh Guillén López, and AMLO's pre-tariff posture of "managed acceptance with humanitarian conditions" — characterised the acceptance of MPP returnees as a non-acquiescence-but-cooperation posture rather than a Safe-Third-Country designation that Mexico had consistently refused since the 2002 Bush proposal.
The May–June 2019 tariff-threat episode was the formative coercive moment of the post-NAFTA bilateral and established the template that Trump-2 would re-deploy in 2024–25. On 30 May 2019, President Trump announced via Twitter a 5 per cent tariff on all Mexican imports under the International Emergency Economic Powers Act (IEEPA), to escalate by 5 percentage points monthly to 25 per cent unless Mexico halted migrant flows. The Ebrard–Mnuchin–Pompeo negotiation between 3 and 7 June 2019 in Washington produced the Joint Declaration of 7 June 2019 under which Mexico committed to (a) accept expanded MPP returns across the entire border; (b) deploy the newly-created Guardia Nacional to the southern border with Guatemala; and (c) take "unprecedented steps to increase enforcement to curb irregular migration." In exchange the United States suspended the tariff threat. Within Mexican political commentary (Castañeda, Dresser, Bravo Regidor, Pérez Ricart), the Joint Declaration was widely characterised as the moment that Mexico — under AMLO's first-year posture — accepted operational outsourcing of US immigration enforcement in exchange for trade-relationship preservation. Tonatiuh Guillén López, the INM Commissioner who had argued for a humanitarian-protection-first posture, resigned within 10 days of the Joint Declaration and was succeeded by Francisco Garduño Yáñez, a security-background figure aligned with the operational enforcement turn.
The March 2020 Title 42 Public Health Order, issued by CDC Director Robert Redfield on 20 March 2020 under 42 U.S.C. § 265 and citing the SARS-CoV-2 pandemic emergency, suspended the introduction of non-citizens crossing the southern border and authorised their immediate expulsion without asylum processing. The order was renewed by both the Trump-1 and Biden administrations and remained in force for 38 months until its 11 May 2023 termination. During its operation CBP recorded approximately 2.8 million Title 42 expulsions, of which the majority involved Mexican nationals and Northern-Triangle Central Americans who could be returned through land ports of entry under bilateral arrangements quietly negotiated between DHS, INM, and SRE. The Mexican government accepted Title 42 returns of its own nationals and, after subsequent negotiation, of designated Central American nationalities — an operational accommodation that the AMLO administration justified through the Estrada Doctrine of non-intervention rather than as endorsement of the US public-health framing.
The CBP One mobile application was launched by US Customs and Border Protection on 12 January 2023 for limited functions and on 5 May 2023 — six days before Title 42 termination — for asylum-appointment scheduling. The application provided approximately 1,450 daily appointments at eight southwest border ports of entry (Brownsville, Eagle Pass, El Paso, Hidalgo, Laredo, Nogales, San Ysidro, and Calexico West, with the precise port-distribution evolving across 2023–25) to non-Mexican asylum-seekers physically present in central or northern Mexico. Between May 2023 and January 2025 the application processed approximately 936,500 appointments [TBD-VERIFY: CBP cumulative figure as of 19 January 2025]. The CBP One architecture became, in Migration Policy Institute analyses by Andrew Selee and Ariel Ruiz Soto, the most consequential operational innovation of the Biden-era border architecture — a "queue-from-Mexico" system that converted irregular border crossing into scheduled port-of-entry processing while maintaining the legal fiction that asylum was not being adjudicated extraterritorially. The Mexican government did not formally co-administer the CBP One system but acquiesced in its operation on Mexican territory and provided humanitarian visas (tarjetas de visitante por razones humanitarias) to extend the legal stay of CBP One waitlist applicants.
The 27 March 2023 fire at the Instituto Nacional de Migración's Estación Migratoria in Ciudad Juárez killed 40 detainees (39 immediate; one in the days following) and exposed the structural failures of the post-2019 enforcement-turn INM. The fire was started by detainees in protest of imminent transfer; surveillance footage released by Mexican investigative outlets (Reforma, Animal Político, El Universal) showed INM guards walking away from the locked cell as smoke filled the chamber. The 40 dead included Venezuelans, Guatemalans, Hondurans, Salvadorans, and Colombians. The FGR opened Carpeta de Investigación FED/CHIH/JUA/0001135/2023 and in August 2023 indicted INM Commissioner Francisco Garduño Yáñez on charges of ejercicio indebido del servicio público — the first time a sitting INM Commissioner had faced criminal prosecution for operational conduct. Garduño remained in office for an additional 16 months under AMLO's protection (AMLO publicly defended Garduño in mañaneras) before resigning shortly before the Sheinbaum transition. The fire became the principal documented evidence of what WOLA, CNDH (Recomendación 38/2023), and the Migration Policy Institute characterised as the institutional collapse of the Mexican migration-detention system under the 2019–24 enforcement load.
The Sheinbaum government's 25 November 2024 response to President-elect Trump's first-day-in-office 25 per cent tariff threat (announced via Truth Social on 25 November 2024) framed the entire 2025 migration-cooperation architecture. Sheinbaum's same-day public letter to Trump asserted that "caravans no longer arrive at the northern border" as a result of Mexican enforcement (a defensible characterisation given the post-2023 caravan-management record); that tariff imposition would harm both economies; and that the bilateral required cooperation rather than coercion. The December 2024 operational deployment of approximately 10,000 Guardia Nacional troops along the northern border under the Plan Frontera Norte framework — announced by Defence Secretary Ricardo Trevilla Trejo and SSPC Secretary Omar García Harfuch, and formalised through the 3 February 2025 telephone call between Sheinbaum and Trump that produced the 30-day tariff pause — replicated the 2019 Joint Declaration template at greater scale and with explicit Estrada-Doctrine framing. The Sheinbaum government characterised the deployment as a sovereign Mexican decision to address transnational organised crime and migration flows, not as outsourced US enforcement. The same deployment was characterised in Washington commentary (CFR, CSIS, Brookings) as the principal Mexican concession that produced the 30-day tariff suspension.
The 20 January 2025 Trump-2 executive-order cascade restructured the entire US immigration architecture in a single day. EO 14159 (Protecting the American People Against Invasion) declared an immigration emergency, suspended refugee admissions, and directed expanded interior enforcement. EO 14165 (Securing Our Borders) terminated the CBP One asylum-appointment system, suspended the parole programmes for Cubans, Haitians, Nicaraguans, and Venezuelans (the "CHNV" parole), reinstated and expanded MPP returns, and directed the construction of additional border barriers. Proclamation 10888 invoked the Article IV Section 4 "invasion" clause as additional authority. The CBP One application was rendered non-functional for new asylum appointments on the morning of 20 January 2025; approximately 30,000 individuals with pending appointments lost access to the system within hours [TBD-VERIFY: precise figure]. The remaining MPP enrollees — those returned to Mexico under the 2019–21 protocols who had not yet received final adjudication — were re-activated for processing under the new MPP architecture, though operational re-launch remained partial through May 2025.
The 15 March 2025 invocation of the Alien Enemies Act (50 U.S.C. § 21–24), a 1798 statute previously invoked only during the War of 1812, the First World War, and the Second World War (the latter producing the Japanese-American internment), was the most legally consequential migration-enforcement action of the Trump-2 first hundred days. The Presidential Proclamation designated Tren de Aragua — the Venezuelan-origin transnational criminal organisation that had expanded into Colombia, Peru, Chile, the United States, and Mexico across 2018–24 — as conducting an "invasion" or "predatory incursion" of the United States and directed the summary apprehension and removal of Venezuelan nationals aged 14 and older alleged to be Tren de Aragua members. Approximately 238 Venezuelan nationals were transferred from US custody to El Salvador's Centro de Confinamiento del Terrorismo (CECOT) megaprison on 15–16 March 2025 under a bilateral arrangement between the Trump-2 administration and President Nayib Bukele's government, without individual removal proceedings or asylum adjudication. The transfers became the subject of immediate litigation — J.G.G. v. Trump in the District of Columbia produced an emergency restraining order from Chief Judge James Boasberg that the administration was alleged to have substantially circumvented — and produced a constitutional crisis around executive-judicial relations that remained unresolved as of May 2025. The Mexican government's posture on the Alien Enemies Act invocation was that of formal non-comment while raising concerns about due process through diplomatic channels; the SRE under Juan Ramón de la Fuente operated through the consular network to assist Mexican nationals not subject to the Alien Enemies Act but exposed to expanded interior enforcement.
The remittance architecture through the 2018–2025 period was the principal stabilising element of the bilateral migration relationship from the Mexican perspective. Banxico recorded annual remittance inflows of $33.7 billion (2018), $36.0 billion (2019), $40.6 billion (2020), $51.6 billion (2021), $58.5 billion (2022), $63.3 billion (2023), $64.7 billion (2024), and a 2025 projected trajectory of approximately $67–70 billion [TBD-VERIFY: Banxico 2025 monthly trajectory and full-year projection range]. Remittances surpassed foreign direct investment in 2021 and have remained Mexico's single largest source of foreign-exchange inflow since. The sectoral geography of dependence — Michoacán, Guanajuato, Oaxaca, Zacatecas, Guerrero, and parts of Jalisco and Chiapas drawing 8–12 per cent of state GDP from remittance flows — has been a structural constraint on any Mexican government's willingness to escalate migration-cooperation disputes. The 2025 Trump administration's introduction of an excise tax on remittances (1 per cent in the May 2025 "Big Beautiful Bill" draft, reduced from earlier 5 per cent proposals) was the most direct policy-instrument challenge to this architecture and was met by Sheinbaum with sustained public opposition. The May 2025 cooperation framework did not resolve the remittance-tax question, which remained the principal unresolved bilateral economic-migration linkage as of mid-2025.
Three contested-record accounts structure the assessment of the 2018–2025 period and remain unresolved. First, the Sheinbaum-Morena sovereignty-and-humanitarian framing: that AMLO and Sheinbaum have managed an extraordinary cross-border-flow shock through formal-protocol cooperation, Estrada-Doctrine preservation of sovereignty, consular-network expansion, and humanitarian acceptance of returnees — with the 2025 Plan Frontera Norte as a sovereign Mexican response to transnational organised crime rather than US-coerced enforcement. Second, the US-Trump-2 enforcement-and-fentanyl framing: that the United States faces an unprecedented invasion of irregular migrants, fentanyl, and transnational criminal organisations; that CBP One functioned as a "legal-immigration on-ramp" that should be terminated; and that Mexican cooperation must be coerced through tariffs, Alien Enemies Act invocations, and FTO-designation leverage. Third, the structural reading of asymmetric border cooperation under interdependence: that a $30-trillion-GDP economy with the world's reserve currency interacts with a $1.8-trillion-GDP economy whose remittances, USMCA trade, and consular-protected diaspora create deep mutual interdependence; that both governments operate through coercion-and-accommodation cycles formally bilateral but significant driven by US domestic-political requirements; and that the migration architecture is best understood as the routine operating mode of an interdependent system under asymmetric stress. The three accounts are not fully reconcilable and their relative explanatory weight remains contested through 2025.

2. The Pre-2018 Baseline — Bracero, IRCA, IIRIRA, Plan Mérida, and Programa Frontera Sur

The bilateral migration architecture inherited by the AMLO administration in December 2018 was the cumulative product of seven decades of US legislation, Mexican diplomatic adjustment, and informal-economy adaptation. Five prior episodes shaped what was politically and operationally possible after 2018, and they are summarised here in compressed form (the broader bilateral architecture is anchored at MX-F-01; the Mérida security cooperation is anchored at MX-A-02 and MX-A-03).

The Bracero Programme (1942–64), authorised under the Mexican Farm Labor Agreement of 4 August 1942, recruited approximately 4.6 million Mexican agricultural workers into US farm labour across 22 years and established the institutional template for state-managed circular labour migration that subsequent Mexican governments would invoke as the preferred legal-migration model. Its 1964 termination — driven by US labour-union pressure, agricultural mechanisation, and Kennedy-era civil-rights politics — produced the structural conditions under which Mexican labour migration shifted from documented circular to undocumented permanent.

The Immigration Reform and Control Act of 1986 (IRCA), signed by President Reagan on 6 November 1986, regularised the status of approximately 2.7 million unauthorised migrants, of whom approximately 70 per cent were Mexican nationals. IRCA's employer-sanctions architecture was widely characterised (Massey, Durand, and Malone, Beyond Smoke and Mirrors, 2002) as the policy that converted Mexican labour migration from circular to settled by making repeat border crossing prohibitive. By the 2000s the United States hosted approximately 6.5 million unauthorised Mexican nationals, the largest single national-origin unauthorised population in US history.

The Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA), signed by President Clinton on 30 September 1996, further hardened the enforcement architecture through expedited removal, 3-and-10-year bars on re-entry following unauthorised presence, and the Operation Gatekeeper / Operation Hold the Line border-fortification sequence that physically rerouted unauthorised crossing from urban San Diego–Tijuana and El Paso–Ciudad Juárez corridors into the Sonoran and Chihuahuan deserts. The desert-crossing routes produced the post-2000 migrant-mortality crisis — Pima County (Arizona) records more than 3,800 migrant remains recovered between 2000 and 2024 in southern Arizona alone — that became the principal humanitarian indictment of the post-IIRIRA architecture.

The 2008–21 Iniciativa Mérida (Mérida Initiative), launched October 2007 by Bush and Calderón and authorised by the US Congress in June 2008, provided approximately $3.5 billion in US security assistance to Mexico across its 13-year life. The migration component was secondary to the counter-narcotics component, but Mérida established the operational practice of US–Mexico security cooperation that the post-2014 migration-enforcement turn would build upon. AMLO formally terminated Mérida in October 2021, replacing it with the Entendimiento Bicentenario of 8 October 2021 — a reframing rather than a notable operational change.

The 2014 Programa Frontera Sur, launched 7 July 2014 by Peña Nieto in Tapachula, was the most direct antecedent of the post-2018 Mexican enforcement architecture. Launched in response to the 2014 unaccompanied-child crisis at the US southern border, the programme provided for expanded INM presence along the Guatemala border, increased deportation of Central American transit migrants, and the "Bestia" freight-train interdiction sequence that disrupted the principal transit route from southern Mexico to the US border. The Programa Frontera Sur operationalised the model — Mexican enforcement at the southern border as functional substitute for US enforcement at the northern border — that would become the load-bearing architecture of the 2019 Joint Declaration and the 2024–25 Plan Frontera Norte. WOLA's Isacson and Meyer characterised it as the moment Mexico effectively became the United States' first immigration-enforcement perimeter.

The cumulative effect by December 2018 was a bilateral architecture characterised by extensive formal cooperation through the SRE–State-Department channel, deep operational integration between INM, CBP, and ICE, a Mexican diaspora of approximately 38 million people in the United States (of whom roughly 12 million were Mexican-born, with 4.5–5 million unauthorised), annual remittance flows then approaching $34 billion, and the structural feature that any major US policy change produced immediate and considerable operational consequences for Mexico. AMLO inherited not a clean slate but a deeply institutionalised system.

3. The 2018 Caravan Shock and the AMLO Inheritance — From Tapachula to Tijuana

The October 2018 migrant caravan — the Caravana Migrante organised in San Pedro Sula, Honduras, beginning 12 October 2018 with approximately 160 participants and expanding through Guatemala into Mexico to peak figures of approximately 7,000 across multiple groupings by early November — was the immediate context in which the AMLO administration assumed power on 1 December 2018. The caravan format had emerged from earlier humanitarian-organisation-coordinated movements (notably Pueblo Sin Fronteras coordinations in 2017 and earlier 2018) but the October 2018 caravan was the first to receive sustained US presidential attention. President Trump made the caravan a central element of his October 2018 midterm-election campaigning, deployed approximately 5,800 active-duty US military personnel to the southern border under Operation Faithful Patriot (rebranded Operation Secure Line in late November), and threatened to close the border with Mexico if the caravan was permitted to advance.

The caravan reached Tijuana in mid-November 2018, with approximately 6,000 participants concentrated in the Unidad Deportiva Benito Juárez shelter under conditions of meaningful humanitarian strain. The 25 November 2018 attempt by some caravan participants to approach the San Ysidro port of entry produced a CBP tear-gas response that generated international media attention and provided the symbolic backdrop for the AMLO inauguration the following Saturday. AMLO's transition team — coordinated by Olga Sánchez Cordero (incoming Secretary of the Interior) and Marcelo Ebrard (incoming Secretary of Foreign Relations) — had spent November in informal contact with the outgoing Peña Nieto administration on caravan management, and had announced in pre-inauguration statements an intention to provide humanitarian visas to caravan participants and to pursue a "Plan de Desarrollo Integral para Centroamérica" (Comprehensive Development Plan for Central America) addressing the structural-economic roots of migration through Mexican investment in El Salvador, Guatemala, and Honduras.

The Tonatiuh Guillén López appointment as INM Commissioner (effective 1 December 2018) was the principal personnel signal of the AMLO administration's initial migration posture. Guillén — a former president of El Colegio de la Frontera Norte (COLEF), a Tijuana-based research institution, and Mexico's leading academic scholar of border-region governance — represented the humanitarian-protection-first orientation that the AMLO campaign had articulated. His memoir Migración: La Agenda Pendiente (UNAM, 2020) provides the principal primary-witness account of the seven-month period during which the AMLO administration attempted to operationalise this posture and the May–June 2019 tariff shock that displaced it.

The first months of the AMLO administration saw approximately 14,000 humanitarian visas issued to Central American migrants between January and March 2019 — the largest such issuance in modern Mexican history — and the operational expansion of COMAR (the Mexican refugee-protection agency). COMAR received approximately 70,400 asylum claims in 2019, 41,200 in 2020 (COVID-suppressed), 130,600 in 2021, 118,500 in 2022, and 140,900 in 2023, before declining to approximately 78,900 in 2024 [TBD-VERIFY]. The January 2019 Caravana Hondureña of approximately 12,000 participants crossing the Suchiate River was managed by INM under Guillén through the issuance of one-year humanitarian visas at the crossing — the most expansive humanitarian-protection posture any Mexican administration had adopted, suspended within five months under the operational requirements of the June 2019 Joint Declaration.

The structural backdrop was that the AMLO administration arrived with three migration-policy commitments that the subsequent four years would partially or wholly reverse: (a) humanitarian-protection-first treatment of Central American transit migrants; (b) refusal to accept Safe-Third-Country designation; and (c) the Plan de Desarrollo Integral para Centroamérica as long-term root-cause response. The third commitment received limited operational traction — Sembrando Vida and Jóvenes Construyendo el Futuro were extended to El Salvador, Guatemala, and Honduras at modest scale. The 2019 tariff shock material constrained the first; the second was preserved in formal terms but functionally circumvented by operational acceptance of MPP returns, performing the de facto function of Safe-Third-Country designation without the legal characterisation.

4. The January 2019 Migrant Protection Protocols and the May–June 2019 Tariff Negotiation (Ebrard–Mnuchin)

The 24 January 2019 announcement by DHS Secretary Kirstjen Nielsen of the Migrant Protection Protocols formalised the legal architecture under Section 235(b)(2)(C) of the Immigration and Nationality Act. The provision had been on the statute books since 1996 but had never previously been operationalised at scale: it permits the return of inadmissible aliens arriving from "a foreign territory contiguous to the United States" to that contiguous territory pending removal proceedings. The DHS legal theory was that non-Mexican asylum seekers crossing into the United States from Mexico were properly returnable to Mexico under this provision. The Mexican government's non-acquiescence-but-cooperation posture — articulated by Ebrard at the 24 January 2019 SRE press conference — was that Mexico did not endorse the US legal characterisation but would accept returnees on humanitarian grounds and would provide work permits, health-care access, and education access to those returned.

MPP operational expansion proceeded through 2019 in a sequence of port-of-entry activations: San Ysidro (29 January), Calexico (March), El Paso (March), Laredo (July), Brownsville (July), Eagle Pass (October), and Nogales (January 2020). Approximately 71,000 individuals were returned to Mexico under MPP between January 2019 and January 2021. The principal nationalities returned were Honduran, Guatemalan, Salvadoran, Cuban, and Venezuelan; Mexican nationals were not subject to MPP and continued to be subject to standard expedited-removal procedures. The cohorts returned to Tijuana, Mexicali, Ciudad Juárez, Nuevo Laredo, Matamoros, Piedras Negras, and (briefly) Nogales established the geographic distribution of the encampment phenomenon. The Matamoros encampment — adjacent to the Gateway International Bridge — at its peak housed approximately 2,500 returnees and became the most extensively documented site, with Human Rights First, MSF, the Strauss Center for International Security and Law (Stephanie Leutert and Caitlyn Yates), and The New York Times (Caitlin Dickerson, Miriam Jordan) producing sustained reporting on living conditions, kidnapping incidents, and assaults.

The 30 May 2019 Trump tariff announcement transformed the bilateral architecture. The announcement — delivered via Twitter at 8:31 PM Eastern Time — declared that on 10 June 2019 the United States would impose a 5 per cent tariff on all goods imported from Mexico, escalating by 5 percentage points monthly to a 25 per cent ceiling on 1 October 2019, unless Mexico halted irregular migration flows to the United States. The legal basis cited was IEEPA, the same authority that would be re-invoked in the Trump-2 era. The Mexican response was immediate and structured. AMLO appointed Ebrard as lead negotiator and dispatched him to Washington with a delegation including Jesús Seade (Undersecretary for North America), Martha Bárcena (Ambassador to the United States), and Roberto Velasco. The negotiation between 3 and 7 June 2019 — conducted principally at the State Department with Secretary Mike Pompeo, Treasury Secretary Steven Mnuchin, and Acting DHS Secretary Kevin McAleenan as US principals — produced the 7 June 2019 Joint Declaration of the United States of America and the United Mexican States on Migration.

The Joint Declaration's marked commitments by Mexico were threefold. First, Mexico committed to "Mexico will take unprecedented steps to increase enforcement to curb irregular migration", operationalised through the deployment of the newly-created Guardia Nacional to the southern border with Guatemala (the deployment began within days of the Joint Declaration with approximately 6,000 troops initially, expanded to approximately 21,000 by autumn 2019 distributed between the southern and northern borders). Second, Mexico agreed to "expand the implementation of the Migrant Protection Protocols across its entire southern border" — read, accept MPP returns at all border ports of entry, not merely the four then operational. Third, Mexico agreed to "offer jobs, healthcare and education according to its principles" to MPP returnees. The Declaration also contained a 45-day review clause and a supplementary commitment by the United States to work with Mexico on "regional asylum cooperation arrangements" — the formula that the United States interpreted as a Safe-Third-Country commitment that Mexico continued to refuse to confirm formally.

The Joint Declaration was widely characterised in Mexican political commentary as the moment that AMLO accepted operational outsourcing of US enforcement in exchange for trade preservation. Castañeda's El Financiero and Reforma columns of June 2019 argued that the Declaration was a "capitulación elegante" (elegant capitulation) that traded sovereignty for tariff suspension. Dresser in Reforma characterised it as the moment Mexico "se convirtió en muro" (became the wall). Bravo Regidor in Horizontal argued that the Declaration was rational under the circumstances — the alternative of accepting the tariff escalation would have been economically catastrophic — but that the AMLO administration had failed to extract sufficient compensatory commitments from the United States. From the Trump administration's side, Mnuchin and Pompeo characterised the Declaration in subsequent congressional testimony as a successful exercise of economic leverage that established the template for future bilateral migration management.

The operational consequences were significant. Apprehensions at the US southern border declined from a May 2019 peak of approximately 144,000 monthly encounters to approximately 52,500 by September 2019, a 64 per cent decline that the Trump administration attributed to Mexican enforcement and that academic analyses (Selee and Ruiz Soto at MPI, 2020) attributed to a combination of Mexican enforcement, MPP-induced deterrence, and seasonal factors. Mexican enforcement on the southern border produced a sustained increase in INM detention and deportation activity: INM apprehensions rose from approximately 138,600 in 2018 to 182,900 in 2019, before declining to 87,300 in 2020 (COVID-suppressed), 307,700 in 2021 (the post-COVID rebound and Haitian transit flow), and 444,400 in 2022 — figures that document the operational scale of the post-2019 Mexican enforcement load.

5. The Mexican Enforcement Turn — The Guardia Nacional, the Southern Border, and the Guillén Resignation

The Guardia Nacional deployment to migration enforcement beginning in June 2019 was the first major operational expression of the post-Joint-Declaration architecture. The Guardia Nacional had been created by constitutional amendment on 26 March 2019 as a federal civilian-led security force intended to replace the discredited Federal Police while remaining formally distinct from SEDENA. The 7 June 2019 Joint Declaration's enforcement commitment was the first major operational mission assigned to the new institution. WOLA's Mexican National Guard and the Border report sequence (Isacson, 2019–22) documented that by autumn 2019 approximately 21,000 Guardia Nacional troops were deployed to migration-enforcement tasks: approximately 14,000 along the northern border (intercepting outbound migration toward the United States) and approximately 7,000 along the southern border (intercepting inbound transit migration from Guatemala). The deployment was operationally novel in that the Guardia Nacional had been constitutionally created as a public-security force — not a border-control force — and the migration-enforcement role created persistent legal-doctrinal questions. The 2019 deployment established the precedent that the 2024 Plan Frontera Norte would replicate at greater scale.

The June 2019 Tonatiuh Guillén López resignation was the principal personnel-political consequence of the enforcement turn. The Joint Declaration's enforcement obligations were incompatible with the humanitarian-protection posture Guillén had attempted to institutionalise. He submitted his resignation on 14 June 2019, one week after the Joint Declaration. His successor, Francisco Garduño Yáñez — a security-background figure (former director general of the federal prison administration under the López Obrador transition) — was understood across political commentary (Animal Político, Aristegui, Proceso) as the operational signal of the post-Joint-Declaration shift.

Garduño's tenure (14 June 2019 through mid-2024 resignation) was the principal institutional vehicle for the AMLO-era enforcement turn. Three characteristics structured the period. First, scale: INM apprehensions rose from approximately 138,600 in 2018 to 444,400 in 2022, a 220 per cent increase reflecting both the Joint Declaration's enforcement load and broader regional flow expansion. Second, detention-infrastructure stress: the INM architecture (designed for ~8,000–10,000 detainees across approximately 50 estaciones migratorias) was operating notable above design capacity throughout 2019–24, with Estación Migratoria Siglo XXI in Tapachula and the Ciudad Juárez facility most chronically overcrowded. Third, human-rights deterioration: CNDH issued more than 60 formal recommendations to INM documenting failures across detention conditions, due-process, medical care, and treatment of detained minors.

The Mexican enforcement turn produced a structural-political tension that was never fully resolved within the AMLO administration. The official rhetoric — in mañaneras and SRE statements — continued to assert humanitarian-protection commitment, the Plan de Desarrollo Integral para Centroamérica framing, and rejection of Safe-Third-Country designation. The operational practice, however, was a sustained-and-expanding enforcement regime producing approximately 1.7 million INM apprehensions across 2019–24 cumulatively. The rhetoric-vs-practice gap became one of the principal critical themes of Mexican migration-policy commentary across the AMLO sexenio.

6. The March 2020 Title 42 Public Health Order and the COVID-Era Architecture

The 20 March 2020 CDC Order under 42 U.S.C. § 265, signed by CDC Director Robert Redfield and issued under the public-health-emergency authority cited as response to the SARS-CoV-2 pandemic, suspended "the introduction of certain persons" from Canada or Mexico travelling without proper documentation and authorised their immediate expulsion. The legal architecture was novel — Title 42 of the US Code is the public-health code, not the immigration code — and the operational consequence was to convert the southern border into an asylum-suspension regime that bypassed the Immigration and Nationality Act's asylum-adjudication procedures entirely. The Order was renewed on a 60-day cycle through 2020–22, extended by both the Trump-1 and Biden administrations, and remained in operation for 38 months until its 11 May 2023 termination at the end of the COVID-19 federal public-health emergency.

The operational consequences for the bilateral were structurally significant. First, the scale of expulsions: CBP recorded approximately 2.8 million Title 42 expulsions across the 38-month period, the majority involving Mexican nationals returned directly through ports of entry but with a considerable subset of Northern Triangle Central American nationals (Guatemalans, Hondurans, Salvadorans) returned through informal arrangements between DHS and INM. The Title 42 expulsion architecture functionally replaced the formal removal procedure for the bulk of border encounters, producing the operational consequence that returnees retained no immigration-record disability and could and did re-attempt crossing repeatedly — the post-2020 multi-encounter phenomenon that inflated CBP encounter statistics and complicated their interpretation. Second, the Mexican operational accommodation: the AMLO administration accepted Title 42 expulsions of Mexican nationals as a matter of standard practice (Mexicans had always been returnable across the land border) and accepted Central American expulsions under negotiated arrangements that the SRE characterised as humanitarian-emergency cooperation. The acceptance produced a significant operational load on Mexican border-city shelter infrastructure, particularly in Tijuana, Mexicali, Ciudad Juárez, Nuevo Laredo, and Matamoros, where Title 42 expellees joined MPP returnees in encampment-and-shelter populations.

The MPP-Title 42 interaction through 2020–22 produced an operationally complex regime in which two parallel return systems operated simultaneously. MPP returns continued through January 2021 (with new enrolments suspended on 21 January 2021 by the incoming Biden administration), while Title 42 expulsions operated as the principal return instrument for all nationalities. The Matamoros encampment, which by mid-2020 housed approximately 2,500 MPP-returnees in conditions documented by MSF (No Way Out, 2020) as among the most dangerous in the hemisphere, was meaningful reduced through the early-2021 Biden transition's Operation Allies sequence that processed approximately 12,000 MPP enrollees into US asylum procedures.

The COVID-era flow disruption was the principal mitigating factor in the operational stress of the period. INM apprehensions declined from approximately 182,900 in 2019 to 87,300 in 2020 — the lowest figure since 2014 — reflecting the COVID-era global mobility suppression. CBP southwest-border encounters declined from approximately 977,500 in FY2019 to approximately 458,100 in FY2020. The 2021 post-COVID rebound, however, produced the largest single-year increase in border encounters in recorded history: CBP recorded approximately 1.73 million encounters in FY2021, rising to 2.38 million in FY2022 and 2.48 million in FY2023, before declining to 2.14 million in FY2024 and projecting material lower in FY2025 under the Trump-2 enforcement architecture.

The structural significance of the Title 42 period for the bilateral architecture was twofold. First, it normalised the practice of bypassing the asylum-adjudication system through emergency-authority claims — a legal template that the Trump-2 administration would replicate in 2025 through the Alien Enemies Act invocation. Second, it institutionalised the operational practice of US-Mexico return-arrangement negotiation outside formal Safe-Third-Country designation, producing what the Migration Policy Institute characterised as "the Safe-Third-Country regime in everything but name" without the formal legal characterisation Mexico had consistently refused. The post-2023 architecture inherited both legacies.

7. The Biden Transition, MPP Rescission Litigation, and the Biden v. Texas Decision (2021–2022)

The 20 January 2021 Biden inauguration initiated a 30-month period of policy reversal, litigation, and improvised operational adjustment that produced the CBP One architecture and the eventual Title 42 termination. Within hours of inauguration, the new Biden administration suspended new MPP enrolments by Acting DHS Secretary David Pekoske; on 1 June 2021 DHS Secretary Alejandro Mayorkas issued a formal memorandum terminating the MPP programme. The Mexican response — articulated by SRE Undersecretary for North America Roberto Velasco at a 1 June 2021 press conference — characterised the termination as a US sovereign decision that Mexico welcomed and that would not affect the bilateral cooperation architecture. The AMLO administration, however, did not relax its enforcement posture on the southern border, where the Programa Frontera Sur / Guardia Nacional deployment continued at scale.

The MPP rescission litigation produced one of the most consequential immigration-law decisions of the period. Texas and Missouri filed Texas v. Biden in the Northern District of Texas, arguing that the Mayorkas termination memorandum violated the APA and that INA Section 235(b)(2)(C) imposed a mandatory return obligation whenever DHS lacked detention capacity. Judge Matthew Kacsmaryk granted the states' motion on 13 August 2021; the Fifth Circuit affirmed. The Biden administration was compelled to re-launch MPP in December 2021 under a more limited "MPP 2.0" architecture. The 30 June 2022 Supreme Court decision in Biden v. Texas, 597 U.S. ___ (2022), reversed the Fifth Circuit and held that Section 235(b)(2)(C) was permissive rather than mandatory (Chief Justice Roberts writing for a 5-4 majority joined by Kavanaugh, Sotomayor, Kagan, and Jackson), permitting formal termination in August 2022. By termination, approximately 7,500 individuals had been enrolled in MPP 2.0, a small fraction of the original 71,000.

The 2021–22 Haitian transit surge was the principal flow-composition shift of the post-MPP period. The September 2021 concentration of approximately 14,000 Haitian migrants under the Del Rio International Bridge between Ciudad Acuña and Del Rio produced the first significant Biden-era operational crisis. The Mexican response — facilitating encampment dispersion through humanitarian visas and operational tolerance of onward transit — was characterised by US commentary as Mexico declining to absorb the Haitian flow that Title 42 expulsions were attempting to return. The 2021–22 Venezuelan flow expansion was more structurally consequential: by 2023 Venezuelans accounted for approximately 25 per cent of CBP southwest-border encounters of non-Mexicans. The Biden administration's October 2022 CHV parole programme (Nicaraguans added in January 2023 as CHNV) parolled approximately 530,000 individuals through January 2025 via monthly caps and US-sponsor requirements before its Trump-2 termination. The Mexican government cooperated with the parole architecture through visa-issuance facilitation but did not formally co-administer it.

8. The 12 January 2023 CBP One Launch and the 11 May 2023 Title 42 Termination

The CBP One mobile application was launched by US Customs and Border Protection on 12 January 2023 for limited functions (cargo trucker scheduling, I-94 processing) and expanded on 18 January 2023 to permit non-Mexican migrants located in central or northern Mexico to schedule asylum-interview appointments at designated southwest-border ports of entry. The launch architecture provided approximately 750 daily appointments distributed across eight ports; the figure was expanded to approximately 1,450 daily appointments by June 2023. The application operated in English, Spanish, and Haitian Creole; required uploaded photographs, geolocation verification placing applicants in central or northern Mexico, and biographic data; and used a lottery rather than first-come-first-served allocation after February 2023 to prevent the queue-jumping that early-2023 reporting had documented.

The operational logic of CBP One was structurally novel: the system created a "queue-from-Mexico" architecture in which non-Mexican migrants could schedule their port-of-entry presentation in advance, undergo a credible-fear interview, and (in most cases) be paroled into the United States to pursue asylum proceedings. It provided the operational substitute for the Title 42 asylum-suspension regime, channelling asylum-seekers into a scheduled-appointment system that was operationally legible to CBP. Between May 2023 and January 2025 the application processed approximately 936,500 appointments [TBD-VERIFY].

The 11 May 2023 Title 42 termination at the end of the federal COVID-19 emergency required operational reorientation of the southwest-border architecture. The Biden response was the 8 May 2023 Circumvention of Lawful Pathways final rule (the "asylum transit ban"), which presumptively denied asylum eligibility to applicants who had transited a third country without first seeking asylum there, with carve-outs for CBP One appointment-holders, parole-programme participants, and unaccompanied minors. The rule was subsequently litigated (East Bay Sanctuary Covenant v. Biden) and partially vacated then stayed pending appeal, but operationally remained in force through May 2025.

The Mexican government acquiescence in the CBP One architecture was operationally consequential despite no formal co-administration. SRE, INM, and COMAR cooperated through three mechanisms: tarjetas de visitante por razones humanitarias issued at scale to CBP One waitlist applicants providing legal stay during the typical 6–9 month waiting period; INM operational tolerance of waitlist concentrations in Tapachula, Mexico City (where Casa del Migrante and other shelter infrastructure expanded), and the northern-border cities; and SRE coordination with US consular operations on humanitarian parole-eligible documentation for CHNV applicants. The cumulative effect was the operational integration of Mexican migration governance into the Biden-era US asylum-processing architecture without formal characterisation as such.

The post-Title-42 flow trajectory displayed a structural shift in encounter composition that conditioned subsequent policy. CBP southwest-border encounters in FY2023 reached approximately 2.48 million, of which approximately 38 per cent were non-Mexican non-Northern-Triangle nationalities (Venezuelans, Cubans, Haitians, Nicaraguans, Colombians, Ecuadorians, Chinese, Indian, and others) — a marked shift from the pre-2018 architecture's 90-per-cent Mexican-or-Northern-Triangle composition. Three consequences followed: return arrangements were complicated (many new-composition nationalities had no functional return option); the Venezuelan-concentration phenomenon emerged that the Trump-2 administration would invoke to justify the Alien Enemies Act invocation; and the political vulnerability — the perception that the US border had become functionally unmanageable — emerged that the November 2024 Trump election would draw upon decisively.

9. The 27 March 2023 Ciudad Juárez INM Detention-Centre Fire and the Garduño Indictment

The 27 March 2023 fire at the INM Estación Migratoria on Avenida Manuel Doblado in Ciudad Juárez, Chihuahua, killed 40 detainees — 39 immediately and one in the days following — and constituted the most consequential single event in the post-2019 Mexican migration-enforcement architecture. The fire began at approximately 9:30 PM local time when detainees set fire to mattresses in protest of imminent transfer (the precise motivation remained contested in subsequent reporting). Surveillance footage subsequently released by investigative outlets (Reforma, Animal Político, El Universal) showed INM guards and Guardia Nacional personnel walking past the locked cell as smoke filled the chamber without unlocking the door or attempting evacuation. The 40 dead included approximately 28 Guatemalans, 7 Venezuelans, 6 Hondurans, 6 Salvadorans, 1 Colombian, and 1 Ecuadorian [TBD-VERIFY: precise nationality distribution from FGR records]. An additional 27 detainees were injured.

The FGR investigation opened Carpeta de Investigación FED/CHIH/JUA/0001135/2023 within 48 hours. The initial charges — homicidio, lesiones, daños al patrimonio cultural, and ejercicio indebido del servicio público — were brought against five INM officials and three private-security personnel contracted by INM. In August 2023 the FGR filed formal charges against INM Commissioner Francisco Garduño Yáñez himself, alleging ejercicio indebido del servicio público on the basis that the Commissioner's operational decisions had created the conditions for the deaths. The indictment of a sitting INM Commissioner for operational conduct was unprecedented in modern Mexican history. The legal proceedings against Garduño proceeded slowly through 2023–24, with multiple procedural delays, and Garduño remained in office throughout — protected publicly by AMLO in mañaneras of late March and April 2023 in which the President characterised Garduño as a "hombre honesto" who would not be made the scapegoat.

The CNDH Recomendación 38/2023, issued on 27 June 2023, documented systematic INM failures across the entire detention architecture: chronic overcrowding (the Ciudad Juárez facility had been operating at 232 per cent of design capacity at the time of the fire); absence of fire-suppression equipment; absent or inadequate training of detention personnel; deficient medical screening; and a culture of impunity for human-rights violations. The Recomendación catalogued the cumulative deterioration of the INM detention architecture across the 2019–23 enforcement-load expansion. WOLA's Maureen Meyer and the Migration Policy Institute's Ariel Ruiz Soto produced post-fire analyses (The Ciudad Juárez Fire and the Failure of Mexico's Migration System, 2023) arguing that the fire was the predictable consequence of a detention architecture that had been operating at scale incompatible with its institutional capacity for at least four years.

The political consequences within the AMLO administration were limited in the immediate term but cumulative across 2023–24. AMLO declined to dismiss Garduño, characterising the FGR proceedings as the appropriate judicial process. Within the Morena coalition the fire produced some critical pushback but did not generate sustained intra-coalition opposition. Within broader political commentary the fire became the principal documented evidence for the WOLA / MPI / CNDH critique of the AMLO-era architecture: that the humanitarian-rhetoric vs enforcement-practice gap had produced an institutional architecture structurally dangerous for the migrants it processed. Garduño formally left INM in mid-2024 (replaced by Francisco Javier Calderón Pérez); proceedings against him remained pending through May 2025 without final disposition, and broader institutional accountability for the fire remained significant unresolved.

10. The 2023–2024 Mixed-Composition Flows — Venezuelans, Cubans, Haitians, and Tren de Aragua

The flow composition of the post-Title-42 period was the structural feature that distinguished the 2023–25 architecture from all prior bilateral migration episodes. Where pre-2018 flows had been predominantly Mexican-and-Northern-Triangle and where 2018–22 flows had begun to diversify with Cuban and Venezuelan participation, the 2023–24 architecture saw sustained-scale arrivals of Venezuelans, Cubans, Haitians, Colombians, Ecuadorians, Chinese nationals, Indian nationals, and West African nationals at proportions that fundamentally changed operational requirements.

The Venezuelan flow was the largest single composition shift. The cumulative Venezuelan migrant population in Mexico — by IOM Mexico estimates — reached approximately 770,000 by mid-2025 [TBD-VERIFY: IOM and UNHCR figures across 2024–25 estimates vary notable; the figure cited represents the higher end of the range and includes both settled and transit populations]. Within Mexican territory, Venezuelan concentrations developed in Tapachula (the principal southern entry point), Mexico City (where the CDMX government's Casa Refugio Cafemín and other shelters expanded to accommodate Venezuelan families), Monterrey, and the northern-border cities. COMAR processed Venezuelan asylum claims at sustained scale: approximately 27,800 Venezuelan asylum claims were filed in 2022, rising to approximately 43,900 in 2023 before declining in 2024 [TBD-VERIFY: precise COMAR Venezuelan-claim trajectory]. The Venezuelan population was the principal target of the March 2025 Alien Enemies Act invocation, but the pre-2025 architecture had been built around accommodation rather than removal.

The Tren de Aragua expansion was the principal security-policy concern associated with the Venezuelan flow. The organisation — originated in the Tocorón prison in Aragua state, Venezuela, and expanded across the late 2010s into Colombia, Peru, Chile, Brazil, and after 2020 into Mexico and the United States — was estimated by Insight Crime analyses to have approximately 4,000 to 8,000 active members hemisphere-wide by 2024. The organisation's involvement in human-smuggling, extortion, sex-trafficking, and the contract-violence economy attracted sustained US law-enforcement attention through 2022–24. In Mexico, Tren de Aragua presence was documented in Tijuana, Ciudad Juárez, Monterrey, and Mexico City, frequently in conflict with established Mexican criminal organisations over migrant-extortion territories. The Trump campaign's 2024 invocation of Tren de Aragua — most prominently in the September 2024 claims about Aurora, Colorado, which subsequent reporting characterised as considerable exaggerated — became the principal political vehicle for the Alien Enemies Act framing that the March 2025 Proclamation would invoke.

The Cuban and Haitian flows displayed distinct dynamics. The Cuban flow — sustained at scale across 2022–24 following the post-2021 Cuban economic collapse — typically transited through Nicaragua (visa-free for Cubans since late 2021), Central America, and Mexico to the US southwest border, with Cuban arrivals eligible for Cuban Adjustment Act benefits. The CHNV parole programme parolled approximately 110,000 Cubans through January 2025. The Haitian flow — sustained since the 2021 Del Rio episode — included meaningful numbers of Haitian families resident in Brazil and Chile since the 2010 earthquake who undertook secondary migration northward through the Darién Gap.

The Darién Gap transit between Colombia and Panama, a marginal smuggling corridor through the 2010s, became the principal Southern Hemisphere migration route during 2022–24. Panama's Servicio Nacional de Migración recorded approximately 248,000 Darién crossings in 2022, 520,000 in 2023, and 302,000 in 2024 — the largest single-route migration through Latin America in recorded history. The Mexican government engaged through the Los Angeles Declaration on Migration and Protection (10 June 2022) framework with Panama, Costa Rica, Guatemala, and the United States; the post-2024 Trump-2 administration material withdrew from the Los Angeles Declaration architecture, and coordination shifted toward bilateral US-Mexico mechanisms.

The Chinese migrant flow produced sustained arrivals (approximately 37,000 CBP encounters in FY2024, the largest figure since the late nineteenth century) via Ecuador (visa-free for Chinese nationals), Central America, and Mexico. The flow was operationally novel because Chinese-nationality return arrangements with the PRC remained marked constrained, producing the consequence that Chinese arrivals were typically released into US asylum proceedings. EO 14159 in January 2025 directed renewed PRC engagement on return arrangements, with operational results remaining partial as of May 2025.

11. The October 2024 Sheinbaum Inauguration, the November Tariff Threat, and the December Plan Frontera Norte Deployment

The 1 October 2024 Sheinbaum inauguration (anchored at MX-D-01 and MX-D-02) initiated the post-AMLO administration that inherited the operational migration architecture described in Sections 5–10 and that would face the immediate Trump-2 confrontation described in Sections 12–14. The early Sheinbaum migration architecture — as developed across October–November 2024 — combined three principal elements. First, the personnel continuity-and-departure pattern: Rosa Icela Rodríguez Velázquez as Secretary of the Interior (with INM under her portfolio); Francisco Javier Calderón Pérez confirmed as INM Commissioner; Omar García Harfuch at SSPC with the Guardia Nacional reporting line; and Juan Ramón de la Fuente at SRE with the consular-network responsibility. Second, the doctrinal continuity-with-modulation pattern: continued adherence to the Estrada Doctrine and to the rejection of formal Safe-Third-Country designation, but with a more operationally-engaged posture toward US enforcement cooperation than AMLO's mid-tenure rhetoric had suggested. Third, the anticipatory-engagement pattern: Sheinbaum's administration began bilateral engagement with the incoming Trump-2 transition team — through the SRE channel and through Ebrard's USMCA channel — within weeks of inauguration, anticipating the migration-tariff linkage that the campaign had foreshadowed.

The 25 November 2024 Trump Truth Social announcement that "Mexico's tariffs would be 25% on all incoming goods" effective on his first day in office, citing migration and fentanyl, was the immediate trigger for the Plan Frontera Norte architecture. Sheinbaum's same-day public letter to Trump — released through the SRE and Presidencia channels — argued (in translation): "the migration phenomenon and drug consumption in the United States cannot be addressed through tariffs but through cooperation"; "caravans no longer arrive at the northern border"; "fentanyl consumption is a public-health problem within US society that Mexico cannot resolve through trade measures"; and "if the United States imposes tariffs, Mexico will be forced to respond with similar measures." The letter's tone — formal, measured, non-confrontational but not acquiescent — established the rhetorical-diplomatic register that the Sheinbaum government would maintain through May 2025.

The December 2024 operational preparation proceeded across three weeks: SSPC Secretary García Harfuch coordinated with SEDENA Secretary Ricardo Trevilla Trejo on operational planning; the SRE under de la Fuente coordinated with the incoming Trump-2 team (Rubio at State, Noem at DHS, Miller at the White House); and the Presidencia coordinated the parallel Plan México economic framework (announced 13 January 2025; MX-D-02).

The Plan Frontera Norte announcement by Sheinbaum at the 4 February 2025 mañanera (post-Trump call) operationally launched the 10,000-Guardia-Nacional deployment, with the largest concentrations in Baja California, Chihuahua, Coahuila, and Tamaulipas. The official mission set was characterised by SSPC and SEDENA communiqués as "prevención y combate a la delincuencia organizada, el tráfico de personas y el tráfico de fentanilo" — a security-and-organised-crime framing Mexican officials consistently asserted in preference to the migration-enforcement framing US characterisations preferred. Operational practice through February–April 2025, however, included significant migration-interdiction activity. The deployment was characterised by the Sheinbaum government as operationally distinct from the 2019 21,000-troop Joint Declaration deployment in concentrating on the northern rather than southern border, in framing around organised-crime-and-fentanyl, and in being a sovereign Mexican decision rather than a tariff-coerced concession. US commentary (CSIS Berg, Brookings Felbab-Brown, WOLA Isacson) characterised the 2025 deployment as operationally notable equivalent to the 2019 deployment, with the framing differences reflecting domestic political requirements on both sides.

12. The 20 January 2025 Trump-2 Executive-Order Cascade and the CBP One Shutdown

The 20 January 2025 Trump-2 inauguration initiated within hours the most extensive single-day restructuring of US immigration architecture in the post-IRCA era. The principal executive instruments were: Executive Order 14159 (Protecting the American People Against Invasion), declaring an immigration emergency and directing expanded interior enforcement; Executive Order 14165 (Securing Our Borders), terminating the CBP One asylum-appointment system, suspending the CHNV parole programmes, reinstating MPP, and directing additional border-barrier construction; Proclamation 10888 (Guaranteeing the States Protection Against Invasion), invoking the Article IV Section 4 "invasion" clause as additional legal authority; and Executive Order 14163 (suspending the US Refugee Admissions Programme). Subsequent executive orders across January–March 2025 added further architectural elements including the FTO designation of Mexican cartels (EO 14157, anchored at MX-D-03), the IEEPA tariff imposition on Mexico (EO 14195, 1 February 2025), and the Alien Enemies Act invocation (Proclamation 15 March 2025).

The CBP One shutdown was operationally immediate. The application's asylum-appointment functionality was rendered non-functional on the morning of 20 January 2025; an in-application notification informed users that "existing appointments have been cancelled" and that new appointments were not available. Approximately 30,000 individuals with pending appointments lost access to the system within hours [TBD-VERIFY: precise figure varies between CBP and MPI estimates between 30,000 and 280,000 depending on whether "pending" includes future scheduled or extends to waitlisted]. The shutdown produced the immediate operational consequence that the queue-from-Mexico architecture that had structured the Biden-era southwest-border processing was eliminated without operational substitute, producing waitlist concentrations in Tapachula, Mexico City, and the northern-border cities that the Mexican government characterised as a humanitarian-emergency consequence of unilateral US action.

The MPP reinstatement under EO 14165 was operationally partial through May 2025. The reinstatement required negotiation with the Mexican government on the operational parameters — the categories of returnable nationalities, the return ports of entry, the support requirements — and the negotiation proceeded slowly through February–April 2025 under the parallel tariff-and-cooperation negotiation framework. The Sheinbaum government's posture was to accept MPP returns of nationalities for which Mexico had prior bilateral arrangements (effectively, Central Americans and certain Caribbean nationalities) while resisting the application of MPP to nationalities whose return-arrangement architecture remained considerable undeveloped (notably Venezuelans, Chinese nationals, and certain African nationalities). The operational MPP architecture through May 2025 returned approximately 12,000 individuals — a small fraction of the 71,000 returned under the 2019–21 architecture — reflecting both the operational ramp-up time and the Mexican government's selectivity.

The CHNV parole termination produced the immediate consequence that approximately 530,000 parole recipients lost the basis for continued US presence. Litigation (Doe v. Noem in the District of Massachusetts) produced an emergency restraining order on 14 March 2025 that the administration characterised as judicial overreach and that produced one of the principal early Trump-2-era constitutional confrontations between executive and federal judiciary. The Mexican government's posture was that the operational consequences for Mexico — particularly CHNV-paroled individuals potentially returning to Mexico either voluntarily or under removal — required bilateral negotiation; the SRE established a CHNV-specific consular-protection sequence.

The interior-enforcement expansion under EO 14159 produced a meaningful increase in ICE removal operations. ICE recorded approximately 150,000 removals in FY2024 under the Biden administration; the Trump-2 administration pursued material higher volumes through 2025 under Operation Safeguard, concentrating enforcement in Chicago, New York, Los Angeles, Houston, Atlanta, and other sanctuary-policy jurisdictions. Approximately 60–70 per cent of removals to Mexico in early 2025 involved Mexican nationals — the operationally simplest removal category given the long-established bilateral receipt arrangements. The 53-consulate Mexican network expanded operational capacity through 2025 with additional legal-aid resources and consular-protection personnel.

13. The 1 February 2025 IEEPA Tariff Imposition, the 3 February 30-Day Pause, and the 10,000-Troop Framework

The 1 February 2025 Executive Order 14195 (Imposing Duties to Address the Situation at Our Southern Border) imposed a 25 per cent tariff on most goods imported from Mexico into the United States, invoking the International Emergency Economic Powers Act (IEEPA) and citing the cross-border fentanyl flow and irregular migration as the national-emergency justification. The Order was operationally distinct from the May 2019 tariff threat in three respects: it was a formal executive order rather than a Twitter announcement; it imposed a 25 per cent rate immediately rather than the 5-per-cent-escalating-monthly schedule; and it was paired with parallel orders against Canada and China that the administration characterised as a comprehensive trade-and-security re-architecture. The Order's legal architecture — IEEPA as the basis for tariff imposition — was the same as the 2019 framework but was operationally novel as the first IEEPA-based imposition of tariffs on a USMCA partner since the Agreement's 1 July 2020 entry into force. The implications for USMCA's institutional architecture were marked and remained subject to litigation and renegotiation through May 2025 (anchored at MX-B-04 and MX-D-02).

The 3 February 2025 Sheinbaum–Trump telephone call — initiated by Sheinbaum and reciprocated by Trump approximately one hour later — produced the 30-day tariff pause that established the negotiating template for the subsequent months. The significant Mexican commitment was the immediate deployment of 10,000 Guardia Nacional troops to the northern border under the Plan Frontera Norte framework (described in Section 11). The notable US commitment was the 30-day suspension of the 25 per cent tariff to permit negotiation of a more durable arrangement. The Sheinbaum government characterised the agreement in subsequent communications as a sovereign Mexican decision on security policy that produced a tariff suspension as a consequence; the Trump administration characterised it as a successful exercise of economic leverage that produced Mexican enforcement cooperation. Both characterisations were operationally consistent with the agreement; the framing differences reflected domestic political requirements.

The tariff reinstatement and modification sequence across February–April 2025 produced an operationally complex regime that combined active tariffs, sectoral exceptions, and rolling negotiation. The 4 March 2025 reinstatement (after the 30-day pause expired without comprehensive agreement) imposed the 25 per cent tariff on most goods; the 6 March 2025 modification carved out USMCA-compliant goods from the tariff; the 12 March 2025 sectoral tariffs (steel and aluminum at 25 per cent globally) added a parallel architecture; the late-March 2025 automotive tariff at 25 per cent added another sectoral layer; and the 9 April 2025 partial-resolution framework (announced as the basis for the USMCA renegotiation track) introduced country-specific modifications. The operational consequence for the Mexican economy was considerable uncertainty — Banxico's Informe Trimestral Q1-2025 documented the trade-policy uncertainty as the principal downward pressure on growth projections — and the peso traded across a wider range than in any quarterly window since the 2008–09 global financial crisis.

The Banxico response through the tariff window combined policy-rate stability and verbal intervention. The policy rate was maintained at 9.50 per cent through the immediate February shock and reduced to 9.25 per cent in March 2025 and 9.00 per cent in May 2025 in a sequence of moderating moves under Governor Victoria Rodríguez Ceja's leadership. The peso depreciated from approximately 20.4 MXN/USD in mid-January 2025 to approximately 21.3 MXN/USD in early February (a 4.4 per cent depreciation) before partially recovering to approximately 20.8 MXN/USD by early May 2025. The depreciation was meaningful smaller than the 2019 tariff-threat episode's peso movements and was characterised by Banxico and external analysts as evidence of the strengthened FX-architecture of the post-2008 Mexican economy.

The bilateral negotiation channels through February–May 2025 operated through three principal tracks — the Ebrard–Greer USMCA-trade channel, the de la Fuente–Rubio political-diplomatic channel, and the García Harfuch–Noem operational-security channel — described in greater detail at MX-D-02 (trade dimension) and MX-D-03 (security dimension). The three-track architecture permitted the Mexican government to compartmentalise the negotiation across trade, diplomatic, and security domains and to avoid the single-track vulnerability that the 2019 negotiation had exhibited.

14. The 15 March 2025 Alien Enemies Act Invocation and the CECOT El Salvador Transfers

The 15 March 2025 Presidential Proclamation invoking the Alien Enemies Act (50 U.S.C. § 21) against Tren de Aragua was the most legally consequential and constitutionally contested migration-enforcement action of the Trump-2 first hundred days. The Alien Enemies Act, enacted as one of the four 1798 Alien and Sedition Acts, had been invoked only three times previously: by Madison in the War of 1812, by Wilson in WWI, and by Franklin Roosevelt in WWII (the latter producing the Japanese-American internment under Proclamation 2525 of 7 December 1941). The statute permits the President, "whenever there is a declared war ... or any invasion or predatory incursion is perpetrated, attempted, or threatened against the territory of the United States by any foreign nation or government", to direct the apprehension and removal of natives, citizens, denizens, or subjects of the hostile nation aged 14 or older. The Trump-2 Proclamation designated Tren de Aragua as conducting an "invasion or predatory incursion" — the first such use in the statute's 227-year history against a non-state actor in the absence of a declared war. The Proclamation's framing relied on legal theories advanced by White House advisor Stephen Miller and DOJ officials that subsequent constitutional litigation would material contest.

The CECOT transfers of 15–16 March 2025 operationalised the Proclamation. Approximately 238 Venezuelan nationals held in ICE detention were transferred via charter flight to El Salvador's Centro de Confinamiento del Terrorismo megaprison under a bilateral arrangement with President Nayib Bukele's government. The Bukele administration agreed to receive the transferees at approximately $6 million annually for the cohort (per administration statements) and to detain them indefinitely without individual removal proceedings, asylum adjudication, or judicial review of the underlying Tren de Aragua designations. Subsequent investigative reporting (ProPublica, 60 Minutes, The New York Times, Proceso, Animal Político) documented that a marked subset had no documented Tren de Aragua affiliation, with designations made on the basis of tattoos, clothing styles, and unrelated criminal records under standards immigration scholars characterised as inadequately rigorous.

The J.G.G. v. Trump litigation, filed 15 March 2025 in the District of Columbia, sought to enjoin the transfers. Chief Judge James Boasberg granted an emergency oral restraining order on the afternoon of 15 March directing the administration to halt the transfers and return any aircraft already in flight. Subsequent reporting documented that the administration significant circumvented the order: aircraft that had departed before the verbal order arrived in El Salvador, and the administration argued that the order had been verbal-only and that written orders were required for binding effect. The subsequent DC Circuit and Supreme Court J.G.G. docket produced an extended constitutional confrontation between the executive and judicial branches that remained notable unresolved through May 2025.

The Mexican posture on the Alien Enemies Act invocation was formal non-comment combined with considerable concern through diplomatic channels. Sheinbaum's 17 March 2025 mañanera characterised the matter as "a US legal question" while expressing concern for "el debido proceso" and for Mexican-resident family members of affected Venezuelans. The SRE issued a 19 March 2025 communiqué expressing "preocupación" about the precedent and reaffirming Estrada-Doctrine non-intervention. The Mexican consular network expanded engagement with affected Venezuelan families, though Venezuelans were not Mexican nationals and consular authority was operationally limited. The broader implications for the bilateral architecture were threefold: a legal precedent for war-powers authority in non-war immigration enforcement that the Trump-2 administration could potentially invoke against Mexican cartels (the February 2025 FTO designation providing the predicate; MX-D-03); a third-country-detention architecture that bypassed Mexican territory entirely; and an early constitutional-crisis indicator of the Trump-2 administration's posture toward judicial authority, with implications for the broader US institutional stability that the bilateral negotiations operated within.

15. The Mexican Consular Network Response, Programa Paisano, and Dual-Citizenship Promotion

The Mexican consular network in the United States — 53 consulates as of May 2025, the largest single-country consular network in the world — operated as the principal Mexican institutional response to the post-2024 interior-enforcement expansion. The network's geographic distribution reflected historical Mexican migration: meaningful concentrations in California (10 consulates), Texas (10), Illinois (Chicago), Arizona (5), and coverage of the Midwest, Southeast, and East Coast. The annual operational budget (approximately $250 million as of 2024) was material expanded by the Sheinbaum 2025 budget request, with the SRE under de la Fuente identifying consular-protection capacity as the principal post-2024 operational priority.

The consular-protection operational expansion through 2025 included three architectural elements: the Centro de Información y Asistencia a Mexicanos (CIAM) call-centre expanded to 24/7 operation providing legal-referral, family-reunification, and emergency-assistance services; the legal-aid network in partnership with MALDEF, CLINIC, and regional legal-aid providers expanded funded-counsel capacity for Mexicans facing removal; and the Asesoría Legal Externa programme expanded its retainer-counsel architecture for detention review, removal proceedings, and federal-court litigation.

The Programa Paisano — managed by INM since 1989 — provides information, documentation, and reintegration support to Mexicans returning from the United States. The Sheinbaum government's January 2025 announcement of expanded Programa Paisano operations under the México Te Abraza framework allocated additional resources for documentation re-establishment, employment-placement through Servicio Nacional de Empleo, and housing assistance through Conavi in border-region reception facilities. Operational scale through May 2025 remained marked below the requirements anticipated under Trump-2 removal projections.

The dual-citizenship promotion through the SRE's 2025 Programa de Doble Nacionalidad expansion provided streamlined procedures for the approximately 1.5 million US-born children of Mexican nationals eligible for Mexican citizenship registration. The political-economic rationale was both protection (for US-born children of undocumented parents) and economic integration (property-ownership, voting, and inheritance rights in Mexico). The Sheinbaum government did not pursue the explicit US-political-mobilisation approach that some Latin American governments (notably Petro in Colombia) have adopted, preferring formal-consular-channels engagement consistent with the Estrada Doctrine. The Mexican-American advocacy ecosystem (MALDEF, UnidosUS, LULAC) operated with Mexican consular cooperation but without formal political coordination.

16. Remittances 2018–2025 — The $63 Billion Cushion and the Sectoral Geography of Dependence

The remittance architecture through the 2018–2025 period was the principal stabilising element of the bilateral migration relationship from the Mexican perspective and the principal economic variable conditioning the Sheinbaum government's response to Trump-2 pressure. Banxico's monthly Ingresos por Remesas Familiares releases documented the trajectory: $33.7 billion (2018), $36.0 billion (2019), $40.6 billion (2020), $51.6 billion (2021), $58.5 billion (2022), $63.3 billion (2023), $64.7 billion (2024), and an early-2025 trajectory consistent with approximately $67–70 billion annualised [TBD-VERIFY: Banxico Q1-2025 full release and projection range]. The 2020–21 surge — 49 per cent cumulative growth across two years — was attributed by Banxico and external analyses to a combination of US fiscal-stimulus pass-through, COVID-era informal-economy disruption that reduced Mexican domestic income alternatives, and a structural increase in remittance frequency (rather than per-transaction amount) reflecting the expanded population sending money home.

The macroeconomic significance of remittances by 2024 was that they exceeded foreign direct investment ($36.9 billion in 2024) as Mexico's principal foreign-exchange inflow; significant exceeded the value of agricultural exports; equalled approximately 4.0 per cent of GDP; and represented approximately 33 per cent of US-Mexico cross-border financial flows. The FX-stabilising role was particularly pronounced during the February 2025 tariff shock, where remittance inflows continued at typical seasonal patterns even as commercial-trade flows experienced uncertainty-induced disruption — providing a base-line dollar-denominated income flow that reduced the peso's depreciation pressure relative to comparable trade-shock episodes.

The sectoral geography of remittance dependence produced one of the most politically consequential domestic-political variables of the post-2024 period. Banxico's Reporte sobre las Economías Regionales documented remittance shares of state GDP for 2024 as: Michoacán (10.5 per cent), Guerrero (9.8 per cent), Oaxaca (8.6 per cent), Zacatecas (8.1 per cent), Chiapas (7.3 per cent), Hidalgo (6.4 per cent), Guanajuato (6.1 per cent), Puebla (5.4 per cent), Tlaxcala (4.7 per cent), and Nayarit (4.3 per cent) [TBD-VERIFY]. The concentration reflected long-historical migration patterns — Michoacán, Guanajuato, and the historic Bajío region — and the cross-party political-economic stake in remittance protection (Morena-governed and PAN-governed remittance-dependent states alike) was the principal source of cross-party consensus on the Sheinbaum government's posture during the Trump-2 tariff confrontation.

The 2025 remittance-tax episode was the principal direct policy-instrument challenge to the remittance architecture and remained unresolved through May 2025. The Trump-2 administration's "One Big Beautiful Bill" omnibus tax-and-immigration legislation included a proposed excise tax on remittance transfers, initially proposed at 5 per cent before being reduced through congressional negotiation to 1 per cent in the May 2025 draft. The Sheinbaum government's response — through SHCP Secretary Rogelio Ramírez de la O, SRE Secretary de la Fuente, and Sheinbaum herself in multiple mañaneras — was sustained public opposition combined with diplomatic engagement on the legislative text. The notable concerns: the regressive distributional impact (senders are predominantly low-income workers); the displacement-to-informal-channels risk with attendant security and money-laundering consequences; and the bilateral-precedent concern of a US tax on cross-border financial flows to a USMCA partner. The medium-term remittance trajectory through 2025–30 is conditioned by the stock of approximately 38 million Mexican-origin US residents (12 million Mexican-born), the wage-and-employment trajectory of Mexican-origin workers concentrated in construction, agriculture, hospitality, and services, and the post-removal-cohort dynamics whose trajectory remains considerable undetermined.

17. The May 2025 Migration-and-Fentanyl Cooperation Framework — Operational Architecture

The May 2025 cooperation framework was the principal operational outcome of the February–April 2025 bilateral negotiation and provided the working architecture for the bilateral migration-and-fentanyl relationship through the remainder of the Sheinbaum-Trump-2 period covered by this document. The framework was announced in stages across early May 2025 [TBD-VERIFY: precise announcement format — joint statement, Sheinbaum-Trump call read-out, or separate national announcements] and combined elements from the Plan Frontera Norte deployment, the post-MPP migration-management architecture, and the post-FTO-designation fentanyl-cooperation architecture (anchored at MX-D-03).

Its principal elements were: continued Guardia Nacional deployment along the northern border at the 10,000-troop level; enhanced fentanyl-precursor and laboratory-seizure operations by SEDENA and FGR (meaningful exceeding the 2018–23 cumulative); operational adaptation of MPP to post-Title-42 conditions with bilateral protocols on returnable nationalities and return ports of entry; Mexican commitment to invest in northern-border infrastructure under Plan México including expanded detention-and-processing capacity and México Te Abraza reception facilities; enhanced intelligence-sharing between SSPC, FGR, DHS, DEA, and FBI on cartel-figure operations and migrant-smuggling networks; operational coordination on third-country flows (Venezuelan, Cuban, Haitian, Chinese) including humanitarian-visa coordination where return was not feasible; continued bilateral engagement on USMCA with explicit linkage to migration cooperation; and non-resolution of the remittance-tax question and continued operation of selective tariffs on Mexican goods, which remained subject to ongoing negotiation rather than being resolved within the framework.

The material achievements were characterised differently by the two governments. The Sheinbaum government characterised the framework as successful Mexican navigation of an asymmetric coercive moment, with Estrada-Doctrine sovereignty preserved, cooperation framed around organised-crime-and-fentanyl rather than migration-enforcement, and the worst tariff scenarios averted. The Trump-2 administration characterised it as a successful exercise of economic leverage that produced Mexican operational cooperation. MPI and WOLA characterisations across May–June 2025 were that the framework represented an operational accommodation that managed the immediate crisis while leaving marked structural questions unresolved — the remittance-tax question, the long-term MPP architecture, the disposition of CHNV parolees, the Alien Enemies Act precedent, and the USMCA framework heading into the 2026 sunset review. The framework was best characterised not as a stable equilibrium but as the operating mode of an interdependent system under ongoing asymmetric stress, conditioned by the Trump-2 domestic political trajectory, the Sheinbaum coalition's mid-term durability, and the broader regional flow dynamics including the Sinaloa civil war (MX-D-03).

18. The Three-Account Assessment — Sheinbaum-Morena Sovereignty Framing, Trump-2 Enforcement Framing, and the Structural Reading

The interpretive landscape of US–Mexico migration cooperation across the 2018–2025 period was structured by three distinct accounts that remained unresolved as of mid-2025 and that organised academic, policy, and political-commentary engagement with the architecture.

The Sheinbaum-Morena sovereignty-and-humanitarian account characterised the period as one in which successive Mexican governments under AMLO and Sheinbaum had managed an extraordinary cross-border-flow shock through formal-protocol cooperation, Estrada-Doctrine preservation of sovereignty, consular-network expansion, and humanitarian acceptance of returnees. The account emphasised: the 2018–19 humanitarian-visa expansion under Guillén; the post-2019 acceptance of MPP returnees with humanitarian-protection commitments; the COMAR expansion to process record numbers of asylum claims; the Title-42-era operational accommodation framed under the Estrada Doctrine; the post-2023 CBP One cooperation with humanitarian-visa support; the 2024–25 Plan Frontera Norte deployment as a sovereign Mexican security operation; the May 2025 cooperation framework as a successful navigation of asymmetric coercion; and the consular-network expansion as the operational vehicle for Mexican-national protection under Trump-2 enforcement. The account's strongest evidentiary base was in the documentation of Mexican formal-policy commitments, the SRE consular-protection operational expansion, and the institutional differences between Mexico's posture and the more confrontational postures of certain Latin American counterparts.

The US-Trump-2 enforcement-and-fentanyl account characterised the period as one in which the United States faced an unprecedented invasion of irregular migrants, fentanyl, and transnational criminal organisations across the southern border; in which the Biden-era CBP One architecture had functioned as a "legal-immigration on-ramp" that incentivised flow expansion; and in which Mexican cooperation had to be coerced through tariffs, FTO designations, and Alien Enemies Act invocations because voluntary cooperation had proven inadequate. The account emphasised: the 2021–24 CBP encounter levels at historical highs; the fentanyl-overdose mortality crisis in the United States (approximately 75,000 deaths annually at peak); the Tren de Aragua, Sinaloa Cartel, and CJNG expansion into US cities; the 2019 Joint Declaration as evidence that Mexican cooperation expanded under tariff pressure but contracted in its absence; the 2024 election results as democratic mandate for restrictive policy; and the May 2025 cooperation framework as the successful product of multi-instrument leverage. The account's strongest evidentiary base was in CBP encounter statistics, fentanyl-mortality data, the documented expansion of Venezuelan-origin organised crime into the United States, and the operational deliverables of the 2019 and 2025 negotiations.

The structural reading of asymmetric border cooperation under interdependence characterised the period as the routine operating mode of a structurally asymmetric bilateral relationship. The account emphasised: the underlying asymmetry of a $30-trillion-GDP economy with the world's reserve currency interacting with a $1.8-trillion-GDP economy whose remittances, USMCA trade, and consular-protected diaspora create deep mutual interdependence; the historical pattern of US-initiated policy change producing Mexican operational accommodation through formal-protocol channels; the cyclical character of coercion-and-accommodation episodes (2019, 2024–25) that operated within a stable underlying architecture; the limited extent to which any plausible alternative Mexican-government posture — whether more confrontational or more acquiescent — could have produced fundamentally different operational outcomes given the asymmetry; and the structural feature that migration cooperation operates not as a bilateral negotiation between sovereign equals but as the operational management of an interdependent system under asymmetric stress. The account's strongest evidentiary base was in the cumulative comparative analysis of bilateral episodes across multiple US administrations (Bush-Fox, Obama-Calderón, Obama-Peña-Nieto, Trump-1-Peña-Nieto, Trump-1-AMLO, Biden-AMLO, Trump-2-Sheinbaum) and in the institutional-economic analyses of the bilateral architecture by Brookings, CFR, MPI, and academic comparative-migration scholarship.

The three accounts are not fully reconcilable: they privilege different evidentiary bases, temporal-analytical frames, and normative commitments. A productive analytical synthesis recognises that each captures genuine features of the architecture — the Sheinbaum-Morena account correctly identifies the significant Mexican-government agency exercised within asymmetric constraints; the Trump-2 account correctly identifies the genuine US domestic-political pressures around irregular migration and fentanyl; the structural account correctly identifies the underlying institutional architecture within which both governments operate. The 2018–2025 period is most coherently characterised as the latest iteration of a long-running asymmetric-interdependence architecture, characterised by recurring coercion-and-accommodation cycles operating within a stable institutional frame, in which both governments exercise meaningful agency within structural constraints that neither can fully transcend. Historiographical assessment will likely depend on subsequent developments — particularly the 2026 USMCA review, the operational trajectory of the May 2025 cooperation framework, the constitutional resolution of the Alien Enemies Act litigation, and the political-economic trajectory of both administrations.

19. Conclusion — Forward View on Asymmetric Border Cooperation under Interdependence

The US–Mexico migration cooperation architecture between 2018 and 2025 is the principal external-relations theatre of the post-AMLO and Sheinbaum sexenios and the principal Mexican-policy domain in which the structural asymmetries of the bilateral relationship are operationally manifest. The four architectural shifts traced in this document — Trump-1 MPP, Trump-1-Biden Title 42, Biden CBP One, Sheinbaum-Trump-2 Plan Frontera Norte / Alien Enemies Act — constitute a single inherited-and-renegotiated system whose operational logic, institutional architecture, and political-economic foundations have remained notable stable across multiple political transitions on both sides of the border. The architecture's stability under stress — its capacity to absorb the 2019 tariff threat, the COVID-era flow disruption, the post-Title-42 composition shift, and the 2024–25 tariff-fentanyl confrontation without structural collapse — is the principal considerable achievement of the bilateral relationship in the period.

Three forward-looking variables condition the 2025–30 trajectory. First, the USMCA 2026 sunset review (anticipated at MX-O-02) provides the principal scheduled inflection point for the trade-migration linkage; the Trump-2 administration's posture will meaningful determine whether the migration-cooperation framework continues to operate within the USMCA institutional frame or shifts to a more bilateral-transactional architecture. Second, the Sheinbaum sexenio mid-term political trajectory — including the 2027 midterms and the operational performance of Plan México — will determine Mexican negotiating flexibility through 2028–30. Third, the Trump-2 domestic and constitutional trajectory — including the resolution of the Alien Enemies Act litigation, the 2026 US midterm elections, and executive-judicial relations — will determine the bargaining environment.

The principal interpretive contribution of the 2018–2025 architecture for the longer-term trajectory is the documentation that migration cooperation operates as the routine operating mode of an interdependent bilateral system under asymmetric stress — a characterisation that is likely to remain analytically productive across multiple subsequent administrations on both sides of the border. Historiographical assessment will material depend on the subsequent trajectory: if the 2025 framework proves durable through 2026–28 and the worst Alien Enemies Act and tariff scenarios are averted, the period will likely be characterised as one in which Mexican-government adaptive capacity successfully navigated an asymmetric coercive moment; if the framework collapses, as one in which structural asymmetries overwhelmed Mexican capacity. This document — the migration-cooperation anchor for the period — connects to MX-F-01 (bilateral architecture), MX-B-04 (USMCA), MX-D-02 (Sheinbaum operational programme), and MX-D-03 (security and cartel-FTO architecture), and anticipates future corpus extensions on the 2026 USMCA review, the post-2025 fentanyl architecture, and the consular-network expansion through the Trump-2 period.

Document End. Version Date: 2026-05-16. Status: [DRAFT]. Word count target: 10,000–14,000.

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MX-A-02: Calderón Presidency (2006–2012) — deep antecedent; Iniciativa Mérida 2008 launch
MX-A-03: Peña Nieto Presidency (2012–2018) — Programa Frontera Sur 2014 launch; pre-AMLO migration baseline
MX-C-01: 2018 AMLO Landslide and Morena's Founding Win (electoral mandate antecedent for the AMLO migration posture)
MX-C-02: Cuarta Transformación (4T) Programme — AMLO Presidency 2018–2024 (the AMLO-era migration policy host doc)
MX-D-01: 2024 Sheinbaum Landslide and Morena Supermajority
MX-D-02: Sheinbaum Government — Continuity, Departure, and the Trump-2 Confrontation (2024–2025) (sister anchor; operational programme)
MX-D-03: Sheinbaum Security Policy and the Sinaloa Cartel War (2024–2025) (sister anchor; fentanyl-cartel-migration linkage)
MX-D-04: Implementation of the 2024 Judicial Reform (2025)
MX-F-01: Mexico–US Bilateral Relationship Architecture (host bilateral doc)
MX-B-04: NAFTA Renegotiation and USMCA (2017–2024) — trade-migration linkage
MX-R-01: Mexico Governance Books Canon
US-E-04: Trump-2 Mass Deportation, ICE Operations, and 287(g) Expansion (2025)
MX-D-05: Sheinbaum Year Two: USMCA 2026 Review and Economic Recalibration (2025-2026)
MX-E-02: US-Mexico Trump-2 tariff confrontation 2025-2026
MX-G-02: back-reference added by symmetry sweep
MX-H-PRES-02: Felipe Calderón Hinojosa — A Biography
MX-H-PRES-03: Enrique Peña Nieto — A Biography
MX-H-PRES-05: Claudia Sheinbaum Pardo — A Biography
MX-H-PRES-06: Carlos Salinas de Gortari — A Biography
MX-H-PRES-07: Ernesto Zedillo Ponce de León — A Biography
MX-D-06: Sheinbaum Year Two — USMCA Review, Cartel-FTO Confrontation, Migration Management, and the 2027 Mid-Term Trajectory
MX-N-01: Mexico in International Perceptions — NAFTA Partner and Cartel Imaginary
MX-I-02: The Mexican Armed Forces and the Militarisation of Public Life
MX-O-01: Mexico Megatrends — The 2030s Questions