There are 2 US Post Offices in Perkins County serving a total of 761 residents equating to 381 residents per post office. It's estimated that approximately 1,215 packages are handled across the 2 county post offices annually. Perkins County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 2,982. Its county seat is Bison. The county was established in 1908 and organized in 1909. It was named for Sturgis, South Dakota official Henry E. Perkins."