Drug Gangs Taking Over US Public Lands

Pot has been grown on public lands for decades, but Mexican traffickers have taken it to a whole new level: using armed guards and trip wires to safeguard sprawling plots that in some cases contain tens of thousands of plants offering a potential yield of more than 30 tons of pot a year.

Local, state and federal agents found about a million more pot plants each year between 2004 and 2008, and authorities say an estimated 75 percent to 90 percent of the new marijuana farms can be linked to Mexican gangs.

In 2008 alone, according to the Drug Enforcement Administration, police across the country confiscated or destroyed 7.6 million plants from about 20,000 outdoor plots.