Union County

Also known as Union County, South Dakota, Union County, SD

county in South Dakota, United States

Key facts

Country: United States
State: South Dakota
Founded: April 10, 1862
Seat: Elk Point
Largest community: Dakota Dunes
Total: 467 sq mi (1,210 km )
Land: 461 sq mi (1,190 km )
Water: 6.6 sq mi (17 km ) 1.4%
Estimate 2025: 17,402
Density: 36.5/sq mi (14.1/km )
Time zone: UTC−6 ( Central )
Summer dst: UTC−5 ( CDT )
Congressional district

Article

Union County is the southernmost county in the U.S. state of South Dakota. As of the 2020 census, the population was 16,811, making it the 13th most populous county in South Dakota. Its county seat has been Elk Point since April 30, 1865. Originally named Cole County, its name was changed to Union on January 7, 1864, because of Civil War sentiment.

Union County is part of the Sioux City metropolitan area. The Progressive Farmer rated Union County second in the "2006 Best Place to Live Survey" in the U.S., because "its schools are good, its towns neat and its people friendly".