As of the census of 2000, there were 1,623,018 people, 654,445 households, and 411,645 families residing in the county. The population density was 1,346 people per square mile (520/km²). There were 741,043 housing units at an average density of 615 per square mile (237/km²). The racial makeup of the county was 70.57% Race (United States Census) (58% were Non-Hispanic), 20.54% Race (United States Census) or Race (United States Census), 0.24% Race (United States Census), 2.25% Race (United States Census), 0.06% Race (United States Census), 3.00% from Race (United States Census), and 3.35% from two or more races. 16.74% of the population were Race (United States Census) or Race (United States Census) of any race.. How many more housing units than households were there in the 2000 census?