Intricate US-Mexico Drug Tunnel Found It had lighting, own rail system By Evann Gastaldo, Newser Staff Posted Oct 31, 2013 8:10 AM CDT 24 comments Comments A different drug tunnel. (AP Photo/Alex Cossio) (Newser) – Imagine the frustration: You've just finished your "highly sophisticated" drug smuggling tunnel when the feds find it and shut it down before you can even use it. The latest US-Mexico tunnel to be uncovered ran between San Diego and Tijuana, and it had lighting and even a rail system, CNN reports. It was also deep and "well-built," according to the AP. But "it hasn't been utilized," an Immigration and Customs Enforcement spokesperson says. "We were able to shutter it before it was utilized to bring drugs into the interior." The AP notes that San Diego is a popular location for such tunnels, because its clay-like soil lends itself to digging. More than 75 tunnels have been discovered along the US-Mexico border since 2008, among them an "extraordinary" tunnel uncovered last year.