Drug smuggling tunnel with rail system uncovered on US-Mexico border

The ventilated underground passage runs the length of a football field and also contains reinforced walls and electricity supply.

Authorities have found about 15 sophisticated tunnels on California’s border with Mexico since 2006 - reports The Guardian.

Many tunnels, including the one announced Monday, are in San Diego’s Otay Mesa industrial area, where clay-like soil is conducive to digging and warehouses provide cover.

The cross-border passages date back to the early 1990s and have been used primarily to smuggle multi-ton loads of marijuana. The US Drug Enforcement Administration said in 2020 that they were generally found in California and Arizona and associated with Mexico’s Sinaloa Cartel.

By federal law, US authorities must fill the US side of tunnels with concrete after they are discovered.