South Dakota is divided into 66 counties, each serving as a local unit of government within the U.S. state. These counties manage local services such as law enforcement, courts, land records and elections. For a formal reference to boundaries and names see an official county list or general information about the U.S. state of South Dakota.

County governments typically operate from a county seat, a town or city where administrative offices and courthouses are located. Examples of important county seats include Pierre in Hughes County (the state capital), Sioux Falls in Minnehaha County and Rapid City in Pennington County. The concept of a county seat remains central to local administration and public records.

The counties were created over the 19th and early 20th centuries as settlers moved into Dakota Territory and new local governments formed. Many county names commemorate Native American tribes, early explorers, politicians or geographic features. Notably, one county changed its name in recent years: the county once known as Shannon is now Oglala Lakota County following a community-driven name change.

Two South Dakota counties do not maintain their own separate county-seat facilities. Oglala Lakota County relies on Hot Springs (located in Fall River County) as its administrative center, while Todd County uses Winner (located in Tripp County) for many official purposes. These arrangements reflect historical, geographic and administrative considerations; see the entries for Hot Springs and Winner for local context. South Dakota's postal abbreviation is SD and its FIPS state code is 46.

List of counties (alphabetical)

  • Aurora County
  • Beadle County
  • Bennett County
  • Bon Homme County
  • Brookings County
  • Brown County
  • Brule County
  • Buffalo County
  • Butte County
  • Campbell County
  • Charles Mix County
  • Clark County
  • Clay County
  • Codington County
  • Corson County
  • Custer County
  • Davison County
  • Day County
  • Deuel County
  • Dewey County
  • Douglas County
  • Edmunds County
  • Fall River County
  • Faulk County
  • Grant County
  • Gregory County
  • Haakon County
  • Hamlin County
  • Hand County
  • Hanson County
  • Harding County
  • Hughes County
  • Hutchinson County
  • Hyde County
  • Jackson County
  • Jerauld County
  • Jones County
  • Kingsbury County
  • Lake County
  • Lawrence County
  • Lincoln County
  • Lyman County
  • McCook County
  • McPherson County
  • Marshall County
  • Meade County
  • Mellette County
  • Miner County
  • Minnehaha County
  • Moody County
  • Oglala Lakota County
  • Pennington County
  • Perkins County
  • Potter County
  • Roberts County
  • Sanborn County
  • Spink County
  • Stanley County
  • Sully County
  • Todd County
  • Tripp County
  • Turner County
  • Union County
  • Walworth County
  • Yankton County
  • Ziebach County

Counties remain important for on-the-ground government services, land and tax records, and administration of state and federal programs. For further details about individual counties, including maps, county seats and historical notes, consult the official resources linked above or local county websites.