On a typical day in Bennett County, South Dakota, farmers and ranchers work their fields and tend animals, merchants order inventory and stock shelves, teachers plan and teach classes, health workers aid the infirm in the county hospital or clinic, and women make quilts and heirlooms for their families or the county fair. Life is usually unhurried, with time for chatting with neighbors and catching up on gossip. But Bennett County is far from typical. Nearly a century ago the county was carved out of Pine Ridge Reservation and opened to white settlers. Today Bennett County sits awkwardly...