As of the 2010 United States Census, there were 21,623 people, 9,236 households, and 5,914 families living in the county. The population density was . There were 9,872 housing units at an average density of . The racial makeup of the county was 94.3% white, 1.4% American Indian, 0.5% Asian, 0.4% black or African American, 0.2% Pacific islander, 0.8% from other races, and 2.4% from two or more races. Those of Hispanic or Latino origin made up 3.0% of the population. In terms of ancestry, 32.4% were German, 14.8% were Irish, 13.7% were English, 7.5% were American, and 6.2% were Norwegian.