Over the last few years, Mexican DTOs have been feeling pressure on their smuggling operations from both Mexican and US law enforcement. Human smugglers have also been feeling the same pressure, as detection and interdiction efforts have improved and viable land routes for both drugs and people have been squeezed. Both types of smugglers have had to get creative, and that's where the border tunnel comes into play.
According to press reports that cite US immigration officials, at least 75 border tunnels have been discovered along the US-Mexico border since the 1990s. Although I'm restricted from saying what the actual number is, I know it's higher than 75. Some of these tunnels are small and crudely dug, but others are absolute marvels of construction, taking into account what they're used for and the clandestine circumstances under which they're built. A few of these tunnels have wooden support beams throughout, concrete flooring, extensive lighting, and ventilation systems. Some even have rails for moving carts filled with narcotics headed north into the US - or bundles of money heading south into Mexico.
One of the more sophisticated border tunnels (pictured right) was discovered in January 2006 in a fruit distribution center in Otay Mesa, California. The tunnel went 85 feet underground and emerged a half mile away in Tijuana, where it was used by the Arellano Felix Organization to smuggle drugs into the US.
Several tunnel detection methods are currently in use by border officials, but they all have their drawbacks. These methods include ground-penetrating radar and sonic equipment, but ICE officials will tell you that investigation and good observation methods tend to trump tunnel detection technology.
In 2003, ICE formed the San Diego Tunnel Task force - the only one of its kind, although Nogales has a more informal group with the same mission. It's a multiagency effort, including US Border Patrol, DEA, US Dept of Justice, and US Navy personnel. Typically, most tunnels are discovered when somebody tips off authorities to signs of suspicious work: digging sounds, activity at odd hours, or numerous trucks. Tunnels rarely last more than a couple of months before they are unearthed, border officials said. Once they're discovered, they're filled with concrete - often at great expense. The Otay Mesa tunnel cost $700,000 to fill. Despite the shirt-lived nature of these tunnels, drug smugglers keep digging and human smugglers keep moving people in this often dangerous manner.