CASPER, Wyo.—Caleb Harris wasn’t looking for help. Last fall, the 39-year-old Florida native thought he had his life under control when he started using drugs again. At the time, he was working as a car salesman in Casper and had been out of jail for about two years after serving an eight-year sentence on charges related to his addiction.

Gillette, Wyo.—Everything is suspect out here. Debris scattered along the roadway that would normally go unseen was suddenly being scrutinized: discarded plastic Sprite bottles, tattered garbage bags, pieces of burnt wood and a faded running shoe flung behind a barbed-wire fence. Even a pile of sun-bleached bones likely belonging to a deer or antelope warranted a second look.