Sioux County

Also known as Sioux County, North Dakota, Sioux County, ND

county in North Dakota, United States

Key facts

Country: United States
State: North Dakota
Founded: September 3, 1914 (created), September 12, 1914 (organized)
Named after: Sioux people
Seat: Fort Yates
Largest community: Cannon Ball
Total: 1,128.203 sq mi (2,922.03 km )
Land: 1,094.052 sq mi (2,833.58 km )
Water: 34.151 sq mi (88.45 km ) 3.03%
Estimate 2025: 3,667
Density: 3.393/sq mi (1.310/km )
Eastern portion: UTC−6 ( Central )
Summer dst

Article

Sioux County is a county located along the southern border of the U.S. state of North Dakota. As of the 2020 census, the population was 3,898, and was estimated to be 3,667 in 2025. Its eastern border is the Missouri River and the county seat is Fort Yates.

History