As of the 2010 United States Census, there were 38,664 people, 14,276 households, and 10,675 families residing in the county. The population density was . There were 15,145 housing units at an average density of . The racial makeup of the county was 97.4% White, 0.6% Asian, 0.5% Black or African American, 0.2% American Indian, 0.3% from other races, and 1.1% from two or more races. Those of Hispanic or Latino origin made up 1.4% of the population. In terms of ancestry, 48.7% were German, 14.1% were Irish, 10.9% were English, and 8.8% were American.