On Thursday 12 July 2012, Mexican soldiers found an incomplete drug tunnel inside a warehouse in Tijuana and seized more than 40 tons of marijuana (about 36,300 kg) stockpiled at its entry.[1][2] The passage ran nearly 400 yards, including more than 100 yards into United States territory, but no exit had been built on the American side.[1][2] It was lit and ventilated and fitted with a railcar system, and soldiers also found four moving trucks full of marijuana plus a trailer of dirt and excavation tools in the warehouse.[1]

The find was one of four border tunnels discovered in a single week, and press reports linked the week’s sophisticated passages to the Sinaloa cartel’s expanding control of the border region.[1][2] The Associated Press noted that raids the previous November on two San Diego-Tijuana tunnels had netted a combined 52 tons of marijuana.[1]