| Name | Jefferson County |
| State | Missouri |
| FIPS Code | 29099 |
| County Seat | Hillsboro |
| Timezone | Central Daylight Time (CDT) |
| Population (2022) | 218,628 |
| Population Growth Rate(2000-2022) | 3.66% |
| Majority Ethnicity | White 97.7% |
| Public School Majority Ethnicity | White 88% |
| Partisan Voting Index | Republican:+19 |
| Unemployment Rate (February 2025) | 3.0% |
| Area Code(s) | 636 / 235 / 573 / 314 / 557 |
| Race/Ethnicity | Percentage of Population (2022) |
|---|---|
| White | 97.7% |
| African American | 1.07% |
| Hispanic | 0.11% |
| Asian | 1.06% |
| Native American | 0.03% |
| Hawaiin/Pacific Islander | 0.03% |
| Race/Ethnicity | Percentage of Public School Students (2023) |
|---|---|
| White | 87.89% |
| African American | 3.04% |
| Hispanic | 3.58% |
| Asian | 0.74% |
| Native American | 0.33% |
| Hawaiin/Pacific Islander | 0.28% |