Even if you didn't know that Denver has become America's undisputed stoner capital, there are clues. Like the two Jerry Garcia-themed bars. Or the 24-hour-a-day stand-up-comedy radio station. And the too-perfect-to-be-a-coincidence nickname (Mile High City) and NBA franchise (the Nuggets). But even if you didn't pick up on any of that, there's a good chance you'd notice the smell – skunky, green, a little piney – wafting through an open car window as you cruise along I-25 into town.