A: Black Canyon of the Gunnison in Colorado, beating out the Badlands of South Dakota by a nose.
The nose in question belonged to a morbidly obese lad of 19 who, no doubt depressed at the thought of spending his life alone and unloved, shot himself with a 12 gauge shotgun on the edge of the Badlands. The bullet tore his skull apart and sent his nose flying 34 feet into the parking lot. As such, the suicide is not considered to have taken place inside the park, giving Black Canyon the win!
Better luck next year, Badlands.