As of the 2010 United States Census, there were 19,980 people, 7,720 households, and 5,377 families living in the county. The population density was . There were 8,390 housing units at an average density of . The racial makeup of the county was 95.7% white, 0.4% Asian, 0.3% black or African American, 0.2% American Indian, 2.3% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 6.1% of the population. In terms of ancestry, 29.6% were German, 12.6% were American, 12.1% were English, and 10.7% were Irish.