Tunnels Going to Pot

Authorities recently found 32 tons of pot after stumbling on a well built cross-border tunnel linking San Diego and Tijuana. The agents who made the discovery were surprised. I wonder why; they have found over 70 such tunnels since 10/08, more than in the previous 6 years! Why, the proliferation? Because of increased and improved border crossing and land enforcement by ICE agents. Digging to avoid detection is a natural economic response.