As of the 2010 United States Census, there were 39,628 people, 14,080 households, and 10,677 families living in the county. The population density was . There were 15,979 housing units at an average density of . The racial makeup of the county was 89.1% white, 0.6% black or African American, 0.4% American Indian, 0.3% Asian, 0.1% Pacific islander, 7.9% from other races, and 1.6% from two or more races. Those of Hispanic or Latino origin made up 13.0% of the population. In terms of ancestry, 40.1% were American, 8.8% were Irish, 7.8% were English, and 5.0% were German.