St. Clair County's estimated 2026 population is 249,259 with a growth rate of -0.38% 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 -7.81% 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 (61.16%)
Black or African American (27.99%)
Two or more races (7.07%)
Other race (1.89%)
Asian (1.56%)
Native American (0.3%)
Native Hawaiian or Pacific Islander (0.03%)
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