As Thursday's massive pot seizure in Tijuana demonstrates, tunnels have become an increasingly common way to smuggle enormous loads of heroin, marijuana and other drugs into the country. More than 70 passages have been found on the border since October 2008, surpassing the number of discoveries in the previous six years.
Over 150 tunnels found since 1990More than 150 secret tunnels have been found along the border since 1990, the vast majority of them incomplete, according to U.S. Immigration and Customs Enforcement. Raids last November on two tunnels linking San Diego and Tijuana netted a combined 52 tons of marijuana on both sides of the border.
The latest Arizona tunnel was discovered after state police pulled over a man who had 39 pounds of methamphetamine in his vehicle and mentioned the strip mall.
Mexico-U.S. drug tunnels found in washroom, mall - World - CBC News