O'Fallon is a city located in St. Clair County, Illinois. O'Fallon has a 2025 population of 32,108 . O'Fallon is currently declining at a rate of -0.19% annually and its population has decreased by -0.94% since the most recent census, which recorded a population of 32,413 in 2020.
The average household income in O'Fallon is $131,945 with a poverty rate of 4.39%. The median age in O'Fallon is 36.9 years: 35.1 years for males, and 38.2 years for females. For every 100 females there are 97.5 males.
Data after 2023 is projected based on recent change
The racial composition of O'Fallon includes 72.62% White, 13.61% Black or African American, and smaller percentages for Asian, other race, Native American and multiracial populations.
White (72.62%)
Black or African American (13.61%)
Two or more races (9.3%)
Asian (2.89%)
Other race (1.5%)
Native American (0.07%)
Race | Population | Percentage (of total) |
|---|---|---|
| White | 23,340 | 72.62% |
| Black or African American | 4,375 | 13.61% |
| Two or more races | 2,990 | 9.3% |
| Asian | 928 | 2.89% |
| Other race | 483 | 1.5% |
| Native American | 23 | 0.07% |
Married
Widowed
Divorced
Separated
Never Married
O'Fallon's average per capita income is $64,936. Household income levels show a median of $102,793. The poverty rate stands at 4.39%.
Name | Median | Mean |
|---|---|---|
| Married Families | $146,065 | - |
| Families | $126,776 | $155,518 |
| Households | $102,793 | $131,945 |
| Non Families | $50,481 | $62,451 |
Average Income
Median Household Income
Poverty Rate