As of the 2010 Census, there were 677,560 people, 225,256 households, and 174,062 families residing in the county. The population density was . There were 237,501 housing units at an average density of . The racial makeup of the county was 76.0% white, 11.2% black or African American, 4.6% Asian, 0.3% American Indian, 5.8% from other races, and 2.3% from two or more races. Those of Hispanic or Latino origin made up 15.6% of the population. In terms of ancestry, 21.6% were German, 18.6% were Irish, 13.3% were Polish, 11.1% were Italian, 5.9% were English, and 2.1% were American.