As of the 2010 United States Census, there were 355,329 people, 137,851 households, and 90,892 families residing in the county. The population density was . There were 152,184 housing units at an average density of . The racial makeup of the county was 79.3% white, 11.7% black or African American, 2.7% Asian, 0.4% American Indian, 0.1% Pacific islander, 2.9% from other races, and 2.9% from two or more races. Those of Hispanic or Latino origin made up 6.5% of the population. In terms of ancestry, 33.4% were German, 11.4% were Irish, 10.7% were American, and 8.1% were English.