| Place Name | O'Fallon |
| Place Type | City |
| County | Saint Charles County |
| Area Code(s) | 636 |
| Timezone | Central Daylight Time (CDT) |
| Population (2022) | 79,073 |
| Population Growth Rate (2010-19) | 15.11% |
| Majority Ethnicity | White 87.14% |
| Metro/Micro Stats Area | St. Louis, MO-IL |
| US Congressional District(s) | Missouri 3rdMissouri 2nd |
| State House Districts | 63,64,102,103,107,108 |
| State Senate Districts | 2,23 |
| Race/Ethnicy | Percentage of Population (2021) |
|---|---|
| White | 87.14% |
| African American | 3.99% |
| Hispanic | 0.04% |
| Asian | 4.37% |
| Native American | 0.03% |
| Hawaiin/Pacific Islander | 4.43% |