As of the 2000 United States Census there were 1,199 people, 537 households, and 354 families in the county. The population density was <1/km². There were 718 housing units at an average density of <1/km². The racial makeup of the county was 98.00% White, 0.50% Native American, 0.17% Asian, 0.17% from other races, and 1.17% from two or more races. 0.67% of the population were Hispanic or Latino of any race. 43.8% were of German, 12.4% Irish, 11.9% Norwegian and 7.0% English ancestry. 97.8% spoke English and 2.2% German as their first language. There were 537 households out of which 22.30% had children under the age of 18 living with them, 61.10% were married couplesliving together, 2.40% had a female householder with no husband present, and 33.90% were non-families. 31.30% of all households were made up of individuals and 17.30% had someone living alone who was 65 years of age or older. The average household size was 2.19 and the average family size was 2.74. The county population contained 18.70% under the age of 18, 4.30% from 18 to 24, 20.00% from 25 to 44, 32.90% from 45 to 64, and 24.10% who were 65 years of age or older. The median age was 49 years. For every 100 females there were 106.70 males. For every 100 females age 18 and over, there were 106.10 males. The median income for a household in the county was $25,451, and the median income for a family was $32,292. Males had a median income of $22,424 versus $18,833 for females. The per capita income for the county was $14,422. About 13.30% of families and 17.20% of the population were below the poverty line, including 23.60% of those under age 18 and 15.50% of those age 65 or over.
2010 census
As of the 2010 United States 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.
Politics
Voters in Prairie County have voted for Republican Party candidates in all national elections since 1948.
