St. Clair County's estimated 2026 population is 250,041 with a growth rate of -0.27% in the past year according to the most recent United States census data. St. Clair County is the 9th largest county in Illinois. The 2010 population was 270,368 and has seen a growth of -7.52% since that time.
Data after 2023 is projected based on recent change
Overall: 39.9 years
Female: 40.9 years
Male: 38.6 years
There are 195,281 adults, (44,007 of whom are seniors) in St. Clair County.
Female: 130,583 (51.5%)
Male: 123,111 (48.5%)
The racial composition of St. Clair County includes 60.12% White, 27.88% Black or African American, and smaller percentages for other race, Asian, Native American, Native Hawaiian or Pacific Islander and multiracial populations.
Race | Population | Percentage (of total) |
|---|---|---|
| White | 152,523 | 60.12% |
| Black or African American | 70,726 | 27.88% |
| Two or more races | 19,866 | 7.83% |
| Other race | 5,705 | 2.25% |
| Asian | 4,174 | 1.65% |
| Native American | 642 | 0.25% |
| Native Hawaiian or Pacific Islander | 58 | 0.02% |
St. Clair County's average per capita income is $50,612. Household income levels show a median of $73,854. The poverty rate stands at 13.58%.
Name | Median | Mean |
|---|---|---|
| Married Families | $120,148 | $140,125 |
| Families | $97,289 | $117,809 |
| Households | $73,854 | $96,049 |
| Non Families | $42,031 | $55,053 |
Average Income
Median Household Income
Poverty Rate