As of the 2010 United States Census, there were 16,561 people, 6,811 households, and 4,618 families residing in the county. The population density was . There were 7,521 housing units at an average density of . The racial makeup of the county was 96.8% white, 0.5% black or African American, 0.4% Asian, 0.2% American Indian, 0.9% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 2.1% of the population. In terms of ancestry, 31.2% were American, 21.7% were German, 15.8% were English, and 12.3% were Irish.