As of the 2010 United States Census, there were 21,253 people, 8,133 households, and 5,647 families in the county. The population density was . There were 9,221 housing units at an average density of . The racial makeup of the county was 97.0% white, 0.4% Asian, 0.3% black or African American, 0.1% American Indian, 1.3% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 2.7% of the population. In terms of ancestry, 34.1% were German, 13.1% were American, 11.7% were English, and 11.6% were Irish.