As of the 2010 United States Census, there were 375,992 people, 145,790 households, and 100,866 families in the county. The population density was . There were 156,945 housing units at an average density of . The racial makeup of the county was 88.2% white, 3.7% Asian, 0.8% American Indian, 0.8% black or African American, 0.2% Pacific islander, 3.1% from other races, and 3.2% from two or more races. Those of Hispanic or Latino origin made up 7.7% of the population. In terms of ancestry, 24.9% were German, 14.5% were English, 13.3% were Irish, 5.0% were Norwegian, and 4.9% were American.