As of the 2010 United States Census, there were 40,814 people, 15,532 households, and 11,172 families living in the county. The population density was . There were 17,633 housing units at an average density of . The racial makeup of the county was 97.4% white, 0.4% Asian, 0.2% Pacific islander, 0.2% American Indian, 0.2% black or African American, 0.6% from other races, and 0.9% from two or more races. Those of Hispanic or Latino origin made up 1.5% of the population. In terms of ancestry, 58.7% were German, 8.8% were American, 8.3% were Irish, and 6.2% were English.