The 2010 United States census indicates St. Clair County had a 2010 population of 163,040. This is a decrease of -1,195 people from the 2000 United States census. Overall, the county had a -0.7% growth rate during this ten-year period. In 2010 there were 63,841 households and 44,238 families in the county. The population density was . There were 71,822 housing units at an average density of . 93.9% were White, 2.4% Black or African American, 0.5% Asian, 0.4% Native American, 0.7% of some other race and 2.0% of two or more races. 2.9% were Hispanic or Latino (of any race). 25.9% identified as of German, 10.2% Polish, 9.3% Irish, 8.5% English, 6.5% French, 6.5% American, and 5.1% Italian ancestry.
The 2010 United States census indicates St. Clair County had a 2010 population of 163,040. This is a decrease of -1,195 people from the 2000 United States census. Overall, the county had a -0.7% growth rate during this ten-year period. In 2010 there were 63,841 households and 44,238 families in the county. The population density was . There were 71,822 housing units at an average density of . 93.9% were White, 2.4% Black or African American, 0.5% Asian, 0.4% Native American, 0.7% of some other race and 2.0% of two or more races. 2.9% were Hispanic or Latino (of any race). 25.9% identified as of German, 10.2% Polish, 9.3% Irish, 8.5% English, 6.5% French, 6.5% American, and 5.1% Italian ancestry.