Hughes County, South Dakota Hughes County, South Dakota Hughes County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 17,022, making it the least populous capital county in the nation, and the twelfth-most populous county in South Dakota. Its county seat is Pierre, the state capital. The county was created in 1873 and organized in 1880. It was named for Alexander Hughes, a legislator. Hughes County is part of the Pierre, SD Micropolitan Statistical Area. According to the U.S. Census Bureau, the county has a total area of , of which is land and
South Dakota Highway 391 South Dakota Highway 391 South Dakota Highway 391 (SD 391) is a state highway in the southwestern part of the U.S. state of South Dakota. It travels from Nebraska Highway 27 (N-27) at the Nebraska state line, southeast of Denby, to U.S. Route 18 (US 18) east-southeast of Denby. The highway is located entirely within Oglala Lakota County and in the Pine Ridge Indian Reservation. It is maintained by the South Dakota Department of Transportation (SDDOT), and is not part of the National Highway System. SD 391 begins at the Nebraska state line as a continuation of N-27 and travels