The county is part of theWhite Earth Indian Reservation.[3] It is the only county in Minnesota entirely within anIndian reservation. Mahnomen, East Polk, and Becker counties constitute one of northwestern Minnesota's biggest cattle-raising areas.
The county was created from the east half ofNorman County on December 27, 1906, withMahnomen, a former railway station town, as the county seat. The county was named for the town, the name of which is one spelling of theOjibwe word for "wild rice".[4]
TheWild Rice River enters the county fromClearwater County and flows west through the central part of the county. TheWhite Earth River originates from White Earth Lake on the county's southern border and flows northwest to its confluence with the Wild Rice nearMahnomen. The county terrain consists of low rolling hills, carved with drainages. The eastern part of the county is dotted with lakes and ponds and largely wooded. All non-wooded areas are devoted to agriculture where possible.[5] The county slopes to the west and north, with its highest point near the middle of the east border, at 1,825 ft (556 m) ASL.[6] The county has an area of 583 square miles (1,510 km2), of which 558 square miles (1,450 km2) is land and 25 square miles (65 km2) (4.3%) is water.[7] Mahnomen is one of 17 Minnesota savanna region counties with more savanna soils than either prairie or forest soils.
As of thecensus of 2000, there were 5,190 people, 1,969 households, and 1,366 families in the county. Thepopulation density was 9.3 per square mile (3.6/km2). There were 2,700 housing units at an average density of 4.84 per square mile (1.87/km2). The racial makeup of the county was 62.85%White (3,262 people) 0.13%Black orAfrican American (7 people), 28.55%Native American (1,482 people), 0.06%Asian (3 people), 0.31% fromother races (16 people), and 8.09% (420 people) from two or more races. 0.89% of the population (46 people) wereHispanic orLatino of any race. 29.4% (1525 people) were ofGerman and 17.0% (882 people)Norwegian ancestry.
There were 1,969 households, out of which 32.40% had children under the age of 18 living with them, 51.60% weremarried couples living together, 11.60% had a female householder with no husband present, and 30.60% were non-families. 27.00% of all households were made up of individuals, and 14.90% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.14.
The county population contained 29.20% under the age of 18, 7.20% from 18 to 24, 23.50% from 25 to 44, 23.40% from 45 to 64, and 16.70% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 102.90 males. For every 100 females age 18 and over, there were 98.40 males.
The median income for a household in the county was $30,053, and the median income for a family was $35,500. Males had a median income of $23,614 versus $21,000 for females. Theper capita income for the county was $13,438. About 11.80% of families and 16.70% of the population were below thepoverty line, including 21.30% of those under age 18 and 15.30% of those age 65 or over.
For several decades, Mahnomen County voters have tended to vote Democratic. As of 2020, the county has selected the Democratic candidate in six of the past ten presidential elections. However, since 2016, the county has trendedRepublican, voting for Donald Trump all three times, with Trump increasing his vote share in 2020 and 2024, receiving 53% of the vote in 2024.[15] The county also voted Republican by double-digit margins for every statewide office in the2022 Midterm Elections, potentially signifying a realignment.[16]
United States presidential election results for Mahnomen County, Minnesota[17]