St. Clair County, IL Map
Official Census boundary of St. Clair County, Illinois (FIPS 17163). Turn on flood zones, contours, land cover and school districts, measure distances, or click any spot to inspect it.
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St. Clair County Demographics
Source: U.S. Census Bureau, American Community Survey 2020-2024 5-year estimates.
Population
253,694
Households
100,846
Median household income
$73,854
Median age
39.9 years
Median home value
$180,300
Median gross rent
$1,090/mo
Owner-occupied homes
68.4%
Bachelor's degree or higher
31.8%
Below poverty level
13.6%
Land area
657.7 sq mi
Population density
386 / sq mi