The extensive storm drain systems in Nogales, Ariz., and Nogales, Mexico, have made tunneling a popular choice for drug traffickers in this southwest portion of the United States.
Crudely constructed, the tunnel pictured to the left exited into a storm drain under Nogales, Ariz.
A more sophisticated tunnel was discovered in September 2003: 1,000 feet in length with lighting, ventilation and carts on rails to transport narcotics. Its discovery led to the arrests of a Mexican federal police commander, a former federal police officer and four drug traffickers of the Joaquin "El Chapo" Guzman Loera drug cartel. (Unclassified Government Photo)