Charles Mix County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 9,373. Its county seat is Lake Andes. The county was created in 1862 and organized in 1879. It was named for Charles Eli Mix, an official of the Bureau of Indian Affairs influential in signing a peace treaty with the local Lakota Indian tribes. The easternmost approximately 60% of the county comprises the Yankton Indian Reservation. The Papineau Trading Post, whose building is now in Geddes, South Dakota, was an early county seat. Geddes tried to wrest the county seat from Wheeler in 1900, 1904, and 1908. The Charles Mix County Courthouse in Lake Andes was built in 1918.

Geography

Charles Mix County lies on the south line of South Dakota. Its south boundary line abuts the north boundary line of the state of Nebraska (across the Missouri River, which flows southeastward along the county's south line). A smaller drainage flows south-southwesterly to the river along the east county line, separating it from Bon Homme County. The county terrain consists of rolling hills, mostly dedicated to agriculture. The terrain drops off into the river basin along the county's southwest side, but otherwise generally slopes to the southeast. The county has a total area of 1150 sqmi, of which 1097 sqmi is land and 53 sqmi (4.6%) is water.

Major highways

Adjacent counties

Protected areas

Major lakes

Demographics

2000 census

As of the 2020 census, there were 9,373 people, 3,050 households, and 2,019 families residing in the county. The population density was 8.5 PD/sqmi. There were 3,625 housing units.

2010 census

As of the 2010 census, there were 9,129 people, 3,249 households, and 2,222 families in the county. The population density was 8.3 PD/sqmi. There were 3,849 housing units at an average density of 3.5 /sqmi. The racial makeup of the county was 65.0% white, 31.7% American Indian, 0.2% Asian, 0.1% black or African American, 0.3% from other races, and 2.7% from two or more races. Those of Hispanic or Latino origin made up 1.7% of the population. In terms of ancestry, 30.2% were German, 12.0% were Dutch, 11.7% were Czech, 6.8% were Norwegian, 5.1% were Irish, and 1.8% were American. Of the 3,249 households, 33.7% had children under the age of 18 living with them, 50.0% were married couples living together, 12.9% had a female householder with no husband present, 31.6% were non-families, and 29.0% of all households were made up of individuals. The average household size was 2.63 and the average family size was 3.23. The median age was 38.2 years. The median income for a household in the county was $35,808 and the median income for a family was $46,962. Males had a median income of $33,477 versus $25,740 for females. The per capita income for the county was $17,403. About 17.4% of families and 24.0% of the population were below the poverty line, including 32.9% of those under age 18 and 15.6% of those age 65 or over.

Communities

Reservation

Cities

Towns

Census-designated place

Townships

Unorganized territory

The unorganized territory of Castalia is located in the county.

Notable residents

Politics

Charles Mix County, more akin to the Midwest than the Great Plains, up until recently favored the Democratic Party. It was one of only 130 counties nationwide to be won in 1972 by favorite son George McGovern, and it was only once carried by a Republican nominee between 1932 and 1976 – when Dwight D. Eisenhower swept every county in South Dakota in 1952. Donald Trump in 2016, 2020, and 2024 easily exceeded the previous best Republican performance in the county.