Hughes County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 17,765, making it the least populous capital county in the nation, and the 12th most populous county in South Dakota. Its county seat is Pierre, which is also the state capital. The county was created in 1873, and was organized in 1880. It was named for Alexander Hughes, a legislator. On June 4, 1891, the county's area was increased by the addition of Farm Island, in the Missouri River downstream of Pierre.

The Senate is the upper house of the South Dakota Legislature. It consists of 35 members, one representing each legislative district. It meets at the South Dakota State Capitol in Pierre.