Coincidence or high-minded planning? Free National Park week now coincides with 4/20, the counterculture holiday devoted to all things cannabis, according to backcountry.com. So, if you're one to grab the Phish bootlegs, strap on the Birks, and give Smokey the Bear (Whoa man!) your best illegal smile, don't wander too far off the trail, as Mexican drug cartels have taken over pot cultivation in remote sections of California and Texas national parks. Harsh.