| County: | Prairie County |
| State: | Montana |
| Ex Image: | Typical.Snowday.Terry.JPG |
| Ex Image Size: | 220px |
| Ex Image Cap: | Downtown Terry, Montana during a typical snowy day. |
| Founded Date: | February 5 |
| Founded Year: | 1915 |
| Seat Wl: | Terry |
| Largest City Wl: | Terry |
| City Type: | town |
| Area Total Sq Mi: | 1743 |
| Area Land Sq Mi: | 1737 |
| Area Water Sq Mi: | 5.8 |
| Area Percentage: | 0.3 |
| Population As Of: | 2020 |
| Population Total: | 1088 |
| Pop Est As Of: | 2022 |
| Population Est: | 1107 |
| Population Density Sq Mi: | 0.6 |
| Website: | (Terry Chamber of Commerce) |
| District: | 2nd |
| Time Zone: | Mountain |
| Footnotes: |
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Prairie County is a county in the U.S. state of Montana. As of the 2020 census, the population was 1,088,[1] making it the fifth-least populous county in Montana.[2] Its county seat is Terry.[3] Prairie County was created by the Montana Legislature in 1915 out of parts of Custer, Dawson, and Fallon Counties. The name was selected in a contest and reflects the predominant landscape of the region.[4]
The county was the site of the 1938 Custer Creek train wreck that killed 47 people and injured 75.
According to the United States Census Bureau, the county has a total area of, of which is land and (0.3%) is water.[5]
As of the 2020 census, there were 1,088 people living in the county.
As of the 2010 census, there were 1,179 people, 551 households, and 342 families in the county. The population density was . There were 673 housing units at an average density of . The racial makeup of the county was 96.4% white, 0.5% Asian, 0.2% American Indian, 0.2% from other races, and 2.8% from two or more races. Those of Hispanic or Latino origin made up 1.4% of the population. In terms of ancestry, 44.7% were German, 18.6% were Norwegian, 14.1% were American, 11.8% were Irish, and 9.5% were English.
Of the 551 households, 18.5% had children under the age of 18 living with them, 55.9% were married couples living together, 4.2% had a female householder with no husband present, 37.9% were non-families, and 34.1% of all households were made up of individuals. The average household size was 2.10 and the average family size was 2.67. The median age was 53.6 years.
The median income for a household in the county was $34,896 and the median income for a family was $43,500. Males had a median income of $28,438 versus $21,964 for females. The per capita income for the county was $21,296. About 12.4% of families and 16.9% of the population were below the poverty line, including 34.6% of those under age 18 and 14.5% of those age 65 or over.
Voters in Prairie County have voted for Republican Party candidates in all national elections since 1948 (as of 2024).