Major highways

Adjacent counties

Protected areas^[5]

Lakes^[5]

2020 census

As of the 2020 census, there were 5,315 people, 2,271 households, and 1,400 families in the county.^[14] The population density was 7.5 inhabitants per square mile (2.9/km²). There were 2,927 housing units.

2010 census

As of the 2010 census, there were 5,438 people, 2,392 households, and 1,490 families in the county. The population density was 7.7 inhabitants per square mile (3.0/km²). There were 3,003 housing units at an average density of 4.2 units per square mile (1.6 units/km²). The racial makeup of the county was 82.6% white, 14.3% American Indian, 0.2% Asian, 0.1% black or African American, 0.2% from other races, and 2.6% from two or more races. Those of Hispanic or Latino origin made up 0.7% of the population. In terms of ancestry, 56.9% were German, 12.5% were Norwegian, 8.9% were Russian, 5.4% were Irish, and 3.1% were American.

Of the 2,392 households, 25.9% had children under the age of 18 living with them, 49.2% were married couples living together, 8.9% had a female householder with no husband present, 37.7% were non-families, and 32.8% of all households were made up of individuals. The average household size was 2.21 and the average family size was 2.79. The median age was 47.2 years.

The median income for a household in the county was $39,517 and the median income for a family was $51,250. Males had a median income of $37,857 versus $21,551 for females. The per capita income for the county was $23,716. About 7.5% of families and 14.5% of the population were below the poverty line, including 23.6% of those under age 18 and 14.4% of those age 65 or over.

Cities

• Mobridge
• Selby (county seat)

Towns

• Akaska (Population:77)
• Glenham (Population:112)
• Java (Population:121)
• Lowry (Population:10)

Unincorporated community^[5]

• Sitka

Unorganized territory

• West Walworth
• East Walworth