Stillwater County is a county in the U.S. state of Montana. As of the 2020 census, the population was 8,963. Its county seat is Columbus.

Geography

According to the United States Census Bureau, the county has a total area of 1805 sqmi, of which 1795 sqmi is land and 9.2 sqmi (0.5%) is water.

Major highways

Adjacent counties

National protected areas

Demographics

2020 census

As of the 2020 census, there were 8,963 people living in the county.

2010 census

As of the 2010 census, there were 9,117 people, 3,796 households, and 2,657 families in the county. The population density was 5.1 PD/sqmi. There were 4,803 housing units at an average density of 2.7 /mi2. The racial makeup of the county was 96.8% white, 0.8% American Indian, 0.3% Asian, 0.1% black or African American, 0.4% from other races, and 1.6% from two or more races. Those of Hispanic or Latino origin made up 2.3% of the population. In terms of ancestry, 34.7% were German, 14.1% were Irish, 14.0% were English, 10.8% were Norwegian, and 6.9% were American. Of the 3,796 households, 28.9% had children under the age of 18 living with them, 60.6% were married couples living together, 6.0% had a female householder with no husband present, 30.0% were non-families, and 25.8% of all households were made up of individuals. The average household size was 2.37 and the average family size was 2.84. The median age was 45.7 years. The median income for a household in the county was $57,227 and the median income for a family was $65,438. Males had a median income of $51,830 versus $26,909 for females. The per capita income for the county was $27,168. About 6.0% of families and 9.5% of the population were below the poverty line, including 17.9% of those under age 18 and 7.2% of those age 65 or over.

Politics

Stillwater County is a heavily Republican county in presidential elections. It has not voted for a Democratic presidential candidate since Franklin D. Roosevelt in 1936.

Communities

Town

Census-designated places

Unincorporated communities

Ghost towns