Narco tunnels have proliferated along the US-Mexico border, but it was the Sinaloa cartel that pioneered this method of subterranean smuggling, first in its area of influence along the Arizona border, expanding all along the frontier as the cartel grew in power.
A Mexican soldier stands next to the entrance of a tunnel and packs of marijuana in Tijuana, November 3, 2010. US border police have found a sophisticated drug smugglers' tunnel the length of six football fields linking Southern California with Mexico and arrested two people, authorities said. Agents recovered more than 25 tonnes of marijuana in seizures related to the investigation in both California and Mexico and arrested a US citizen and his Mexican wife.