2020 census
As of the 2020 census, there were 3,837 people, 1,361 households, and 853 families residing in the county. [27] Of the residents, 27.6% were under the age of 18 and 21.2% were 65 years of age or older; the median age was 39.8 years. For every 100 females there were 105.3 males, and for every 100 females age 18 and over there were 101.4 males. [27]
The population density was 4.0 inhabitants per square mile (1.5/km2). There were 1,603 housing units, of which 15.1% were vacant; among occupied housing units, 76.6% were owner-occupied and 23.4% were renter-occupied, with a homeowner vacancy rate of 1.1% and a rental vacancy rate of 5.1%. [27]
The racial makeup of the county was 94.3% White, 0.3% Black or African American, 0.6% American Indian and Alaska Native, 0.2% Asian, 1.7% from some other race, and 2.9% from two or more races. Hispanic or Latino residents of any race comprised 4.4% of the population. [28]
Of the 1,361 households, 25.3% had children under the age of 18 living with them and 20.0% had a female householder with no spouse or partner present. About 33.9% of all households were made up of individuals and 14.5% had someone living alone who was 65 years of age or older. [27]
2010 census
As of the 2010 census, there were 3,691 people, 1,445 households, and 929 families residing in the county. The population density was 3.9 inhabitants per square mile (1.5/km2). There were 1,710 housing units at an average density of 1.8 per square mile (0.69/km2). The racial makeup of the county was 98.1% white, 0.2% black or African American, 0.1% Asian, 0.1% American Indian, 0.8% from other races, and 0.8% from two or more races. Those of Hispanic or Latino origin made up 1.7% of the population. In terms of ancestry, 52.0% were German, 29.4% were Norwegian, 9.7% were Irish, 7.8% were English, 5.4% were Swedish, and 3.5% were American.
Of the 1,445 households, 23.0% had children under the age of 18 living with them, 55.8% were married couples living together, 4.8% had a female householder with no husband present, 35.7% were non-families, and 32.5% of all households were made up of individuals. The average household size was 2.22 and the average family size was 2.79. The median age was 45.7 years.
The median income for a household in the county was $43,894 and the median income for a family was $55,575. Males had a median income of $33,606 versus $24,952 for females. The per capita income for the county was $23,909. About 7.5% of families and 13.1% of the population were below the poverty line, including 24.5% of those under age 18 and 12.6% of those age 65 or over.
United States
South Dakota 
