| Place Name | O'Fallon |
| Place Type | City |
| ZIP Code(s) | 62208 62221 62225 62254 62269 |
| County | Saint Clair County |
| Area Code(s) | 618 |
| Timezone | Central Standard Time (CST) |
| Population (2022) | 28,377 |
| Population Growth Rate (2010-19) | 14.17% |
| Majority Ethnicity | White 77.54% |
| Metro/Micro Stats Area | St. Louis, MO-IL |
| US Congressional District(s) | Illinois 12th |
| State House Districts | 108,112,114 |
| State Senate Districts | 54,56,57 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 77.54% |
| African American | 13.77% |
| Hispanic | 0% |
| Asian | 4.07% |
| Native American | 0% |
| Hawaiin/Pacific Islander | 4.62% |