MEXICO CITY — The Trump administration announced this summer that illegal crossings into the U.S. from Mexico had reached historical lows. Homeland Security Secretary Markwayne Mullin stated, “Our border is CLOSED to lawbreakers.” Despite this, the administration continues to pressure both Mexico and U.S. officials to further curb illegal immigration. This crackdown has led smugglers to adopt more creative methods, increasingly utilizing tunnels that were previously used for drug transportation.
Stephen Miller, the architect of President Trump’s immigration policies, has been in frequent communication with senior U.S. law enforcement officials, including U.S. ambassador to Mexico, Ronald Johnson, to explore new strategies for preventing migrants from entering the United States. In July, an average of 400 migrants were apprehended daily while crossing into the U.S., a significant decrease from the thousands who crossed daily during the peak of a migrant surge in 2022. At times, the daily crossings have dropped to 200.
Miller's goal is to achieve zero migrant entries into the U.S. He has instructed officials to intensify investigations into migrant smuggling networks. Since returning to the White House in 2025, Trump has frequently urged Mexican President Claudia Sheinbaum to take stronger action against immigration. On August 26, Secretary of State Marco Rubio met with Mexico’s foreign minister, Roberto Velasco Álvarez, to advocate for decisive measures against illegal immigration.
The Trump administration's border enforcement has reportedly been effective enough to push some smugglers underground. Mexican drug cartels are increasingly using tunnels built for drug smuggling to transport migrants into the United States, often connecting to sewer drains. Although the number of migrants apprehended using tunnels is relatively small, authorities believe it is on the rise due to the intensified border crackdown and the financial incentives for cartels to smuggle people.
“Enforcement along the border has become more robust, increasing the demand for alternative methods of passage,” said David Shirk, director of the Justice in Mexico program at the University of San Diego. The administration has added more miles of razor wire to border fences, enhanced surveillance technology, and deployed autonomous Predator drones equipped with surveillance and infrared technology to monitor large areas of the border.
In line with Trump’s “build the wall” pledge, additional border barriers are being constructed. Trafficking through cross-border tunnels is not a new phenomenon; in 2023, Ken Salazar, then the U.S. ambassador to Mexico, reported at least 200 tunnels spanning the border, many linking Tijuana and San Diego. Some tunnels now connect to drainage and sewer systems. In May, authorities captured 19 migrants, including three unaccompanied minors, in the San Diego storm water drainage system.
Smugglers are employing tunneling specialists who are enhancing the sophistication of these tunnels, equipping them with lights, ventilation systems, and sometimes mini rail lines. These tunnels are often faster, safer, and more expensive for migrants compared to increasingly perilous mountain and desert routes. Last year, Customs and Border Protection and Homeland Security Investigations agents discovered a tunnel running under the Rio Grande from Ciudad Juárez, Mexico, into El Paso, where migrants surfaced from a manhole and climbed into a box truck parked above.
Cartels charge migrants from Latin America up to $15,000 each to use tunnels to El Paso, while those from the Middle East or Southeast Asia may pay as much as $25,000. The tunnel traffic continues to challenge U.S. officials. In Tijuana, one tunnel discovered last year extended from Tijuana to a seemingly unvisited Buy 4 Less store near the Otay Mesa port of entry. U.S. law enforcement suspected the store was hiding a tunnel and began monitoring it, eventually raiding the location and finding a tunnel controlled by the Jalisco New Generation Cartel.
This tunnel was 55 feet deep and nearly half a mile long, featuring a hydraulic lift, ventilation, and a rail and cart system. Authorities intercepted a freezer truck after it left the site and seized over a ton of cocaine, valued at approximately $45 million. In 2024, U.S. law enforcement discovered another tunnel in San Luis, Arizona, used for smuggling migrants and drugs, with its exit concealed in an abandoned KFC restaurant.