As of the 2010 United States Census, there were 38,431 people, 13,894 households, and 10,240 families living in the county. The population density was . There were 16,004 housing units at an average density of . The racial makeup of the county was 79.6% white, 1.1% American Indian, 0.7% Asian, 0.3% black or African American, 0.1% Pacific islander, 15.6% from other races, and 2.6% from two or more races. Those of Hispanic or Latino origin made up 28.7% of the population. In terms of ancestry, 20.2% were German, 11.2% were English, 9.4% were Irish, 6.0% were Norwegian, and 5.0% were American.