What are the primary smuggling routes into the United States at the southwest border?
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Executive summary
Smugglers use multiple, evolving routes into the United States at the southwest border: official ports of entry (POEs) are a primary venue for drug smuggling because of volume and concealment opportunities, while between‑port routes include remote land corridors, subterranean tunnels, ultralight aircraft/UAS, and maritime approaches off the Pacific and Gulf coasts [1] [2]. Recent enforcement and bilateral actions have reduced detected between‑port encounters, but experts warn lower official encounters can shift smuggling to maritime and more remote routes that are harder to detect [3] [4].
1. Ports of entry: legal crossings exploited for concealment
Official POEs — bridges, vehicle lanes, rail and pedestrian crossings — are used routinely by smugglers because their sheer throughput provides concealment for contraband and human smuggling. Researchers and advocacy groups note that large volumes of vehicles, pedestrians and cargo create opportunities for smuggling at POEs, and FOIA data show most persons arrested smuggling fentanyl at southern POEs were U.S. citizens in a recent sample [1]. Congressional and DOJ reporting also documents that Mexican‑based organizations historically route many drugs through POEs in California and South Texas [1].
2. Between the ports: land routes, tunnels and aerial tricks
Smuggling “between ports of entry” remains a core concern for policymakers. The Congressional Research Service and CRS summaries document that smugglers use land corridors, underground tunnels, ultralight aircraft and unmanned aircraft systems (UAS) to move drugs and people between POEs [2]. Older U.S. government assessments and National Drug Threat products likewise identify the nearly 2,000‑mile southwest border and specific corridors (including reservation and remote border areas) as principal zones for human and drug smuggling [5]. These methods allow traffickers to bypass screening at POEs and exploit remote terrain [2] [5].
3. Maritime lanes and coastal landings are growing pressure points
Law enforcement and local reporting highlight maritime smuggling as a growing alternative when land routes are tightened. CBP and Coast Guard commentary with local media describe dangerous small‑boat voyages off Southern California and other coasts used to move migrants; reporters document tragedies and agency warnings that maritime efforts remain steady even as land encounters fall [6]. Policy analysts and advocacy outlets have raised similar alarms that smugglers redirect operations to coastlines and sea routes when land options constrict [7].
4. Long international chains: charter flights and intercontinental routes
Smuggling networks now frequently begin far from Mexico. Investigations traced charter flights and complex intercontinental chains that move migrants from Africa and Asia toward the southwest U.S. border — often involving commercial and charter aviation then handoffs to regional smugglers for overland or maritime final legs [8]. These findings show smuggling is not only a regional phenomenon but part of global networks feeding border routes [8].
5. Enforcement, cooperation and displacement: fewer detected crossings, different risks
U.S. and Mexican enforcement cooperation, new administrative rules, and technology have coincided with major declines in detected encounters between POEs — DHS cites over a 60% decrease from May–Dec 2024 and CBP/House reports claim historically low apprehension totals in some recent months [3] [9]. Migration policy analysts caution those declines may reflect displacement rather than elimination: stronger enforcement in some corridors can push smugglers to tunnels, maritime routes, or more remote land crossings that increase humanitarian risk and complicate interdiction [4].
6. Organized criminal roles and financial signals
Longstanding U.S. reporting stresses that Mexican drug trafficking organizations (DTOs) and alien smuggling organizations (ASOs) control and monetize routes; ASOs often pay for access to specific corridors and use violence and corruption to maintain operations [5]. Financial crime guidance to banks highlights how smuggling generates identifiable transactional patterns, underscoring the role of follow‑the‑money efforts in disrupting networks [10].
7. What reporting does not specify or quantify
Available sources do not provide comprehensive, current estimates of the share of total smuggling flows by each route (POE vs between‑ports vs maritime vs aerial). Nor do the cited items offer a single authoritative ranking of “primary” routes by volume across 2024–25; instead, they document multiple prominent modalities and recent shifts driven by policy and enforcement [2] [4] [8].
Context and caveats: official counts (encounters, seizures, apprehensions) reflect detection and enforcement emphasis as much as underlying flows; researchers and agencies in the sources warn that declines in detected crossings can mask diversion to harder‑to‑detect maritime and subterranean routes [3] [4]. Different sources emphasize different threat narratives — DHS/CBP highlight decreases and operational successes [3] [11], while independent analysts and investigative reporters point to evolving smuggler tactics and international chains [4] [8].