Lyman County, South Dakota

Lyman County
Location within the U.S. state of South Dakota
South Dakota's location within the U.S.
Coordinates: 43°54′N 99°51′W / 43.9°N 99.85°W / 43.9; -99.85
Country United States
State South Dakota
Founded1893
Named afterW. P. Lyman
SeatKennebec
Largest communityLower Brule
Area
  Total
1,707 sq mi (4,420 km2)
  Land1,642 sq mi (4,250 km2)
  Water65 sq mi (170 km2)  3.8%
Population
 (2020)
  Total
3,718
  Estimate 
(2024)
3,721
  Density2.2/sq mi (0.84/km2)
Time zoneUTC−6 (Central)
  Summer (DST)UTC−5 (CDT)
Congressional districtAt-large
Websitewww.lymancounty.org

Lyman County is a county located in the U.S. state of South Dakota. As of the 2020 census, the population was 3,718. Its county seat is Kennebec.

Lyman County was created by the Dakota Territorial Legislature on January 8, 1873, but was not organized until May 21, 1893. Its boundaries were altered in 1891, 1897, 1898, and 1916. The county was named for W. P. Lyman, a politician.