As of the 2010 United States Census, there were 19,104 people, 8,040 households, and 5,427 families residing in the county. The population density was . There were 9,274 housing units at an average density of . The racial makeup of the county was 98.0% white, 0.3% black or African American, 0.2% Asian, 0.2% American Indian, 0.1% Pacific islander, 0.3% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 1.0% of the population. In terms of ancestry, 34.7% were German, 13.8% were English, 13.2% were American, and 12.1% were Irish.