St. Clair County's estimated 2025 population is 248,524 with a growth rate of -0.5% 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 -8.08% since that time.
Data after 2023 is projected based on recent change
The racial composition of St. Clair County includes 61.16% White, 27.99% Black or African American, and smaller percentages for other race, Asian, Native American, Native Hawaiian or Pacific Islander and multiracial populations.
White
Black or African American
Two or more races
Other race
Asian
Native American
Native Hawaiian or Pacific Islander
Race | Population | Percentage (of total) |
|---|---|---|
| White | 155,810 | 61.16% |
| Black or African American | 71,311 | 27.99% |
| Two or more races | 18,024 | 7.07% |
| Other race | 4,812 | 1.89% |
| Asian | 3,977 | 1.56% |
| Native American | 761 | 0.3% |
| Native Hawaiian or Pacific Islander | 82 | 0.03% |
Married
Widowed
Divorced
Separated
Never Married
St. Clair County's average per capita income is $47,658. Household income levels show a median of $70,178. The poverty rate stands at 13.56%.
Name | Median | Mean |
|---|---|---|
| Married Families | $115,700 | $136,691 |
| Families | $92,727 | $114,036 |
| Households | $70,178 | $92,847 |
| Non Families | $39,591 | $52,329 |
Average Income
Median Household Income
Poverty Rate