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. Its eastern border is the Missouri River and its county seat is Fort Yates.

History

The county was created by proclamation of Governor Louis B. Hanna on September 3, 1914. It was named for the Native American Lakota, whose historic territory included this area. The county government organization was completed on September 12 of that year. The county lies entirely within the Standing Rock Indian Reservation, forming the northernmost 30 percent of the reservation; the balance of the reservation is in South Dakota. It is the only county in North Dakota that is entirely within an Indian reservation. From 2013 to 2018, Sioux County was included in the Bismarck, ND Metropolitan Statistical Area.

Geography

Sioux County lies on the south line of North Dakota. Its south boundary line abuts the north boundary line of the state of South Dakota. Its north boundary line is formed by the east-northeastward-flowing Cedar Creek, which discharges into the Missouri River at the county's northeast corner, and its east boundary line is formed by the south-southeast-flowing Missouri River, which also forms Lake Oahe along the county boundary line. Porcupine Creek flows southeastward into the Missouri River, draining the northeastern part of the county. The county terrain consists of low rolling hills etched with gullies and drainages; the area is mostly devoted to agriculture. The terrain slopes to the east and south; its highest point is on the west line, near the southwestern corner of the county, at 2,602 ft ASL. The county has a total area of 1128 sqmi, of which 1094 sqmi is land and 34 sqmi (3.0%) is water. The southwest corner counties of North Dakota (Adams, Billings, Bowman, Golden Valley, Grant, Hettinger, Slope, and Stark) observe Mountain Time. The counties of McKenzie, Dunn, and Sioux are split, observing Mountain Time in their western portions.

Major highways

Adjacent counties

Protected areas

Demographics

2020 census

As of the census of 2020, there were 3,898 people.

2010 census

As of the census of 2010, there were 4,153 people, 1,158 households, and 900 families in the county. The population density was 3.8 PD/sqmi. There were 1,311 housing units at an average density of 1.2 /sqmi. The racial makeup of the county was 84.1% American Indian, 12.6% white, 0.2% black or African American, 0.1% Asian, 0.1% from other races, and 2.9% from two or more races. Those of Hispanic or Latino origin made up 2.0% of the population. In terms of ancestry, 13.5% were German, and 0.3% were American. Of the 1,158 households, 54.1% had children under the age of 18 living with them, 32.5% were married couples living together, 31.6% had a female householder with no husband present, 22.3% were non-families, and 17.4% of all households were made up of individuals. The average household size was 3.55 and the average family size was 3.89. The median age was 26.3 years. The median income for a household in the county was $30,990 and the median income for a family was $31,098. Males had a median income of $31,894 versus $26,619 for females. The per capita income for the county was $13,542. About 39.0% of families and 47.2% of the population were below the poverty line, including 58.4% of those under age 18 and 36.1% of those age 65 or over.

Population by decade

Communities

Cities

Census-designated places

Township

Politics

With its population being mostly Native American, Sioux County is one of the most consistently Democratic counties in North Dakota, having last backed a Republican presidential candidate in 1980. Since then the closest a Republican has gotten to winning the county was Ronald Reagan in 1984 who lost the county by 19 percent. John Hoeven, in his 2010 election to the Senate, as well as his 2008 reelection as governor, won the county. In 2016, Hillary Clinton won the most votes in Sioux County, one of only two counties she won in the state. Green Party candidate Jill Stein received 10.4% of the popular vote.

Education

School districts include: