Talk about your quagmire. The "War on Drugs" dates back to the Nixon Administration, and it highlights an ever growing need for law-abiding citizens to arm themselves for protection. From CNN:

Drug traffickers are planting millions of marijuana plants on U.S. public lands ever closer to tourist sites, guarding their plots with heavy weaponry, federal authorities say.

"We destroy their plants and they come back, sometimes to the same spot, and replant," said U.S. Forest Service Special Agent Russ Arthur.

"It's definitely possible that hikers and campers are going to find themselves in the middle of a field facing some very dangerous, armed bad guys, because this problem is everywhere, and it's only getting worse."

Guns are currently banned in National Parks thanks to an activist judge, US District Court Judge Colleen Kollar-Kotelly. Judge Kotelly slapped an injunction (citing environmental concerns) on a DOI regulation change to allow the carry of guns in National Parks consistent with state laws (similar to National Forests). Congress has since passed legislation repealing activist Judge Kotelly's ban, but the rules do not change until February 2010.