As of the census of 2010, there were 516,564 people, 140,602 households, and 114,350 families residing in the county. The population density was 259 people per square mile (100/km²).  There were 148,350 housing units, at an average density of 74 per square mile (29/km²). The countys racial makeup was 89.4% Race (United States Census), 0.5% Black or African American, 0.6% American Indian or Alaska Native, 1.4% Asian, 0.8% Native Hawaiian or other Pacific Islander, 4.6% some other race, and 2.7% from two or more races. 10.8% of the population were Hispanic or Latino of any race.. How many more housing units are there than households?