| Name | Jefferson County |
| State | Iowa |
| FIPS Code | 19101 |
| County Seat | Fairfield |
| Timezone | Central Daylight Time (CDT) |
| Population (2024) | 15,626 |
| Population Growth Rate(2020-2024) | -0.26% |
| Majority Ethnicity | White 84.58% |
| Public School Majority Ethnicity | White 85% |
| Partisan Voting Index | Republican:+3 |
| Unemployment Rate (May 2026) | 3.2% |
| Sales Tax Rate (2025) | 7% |
| Area Code(s) | 641 / 319 |
| Race/Ethnicity | Percentage of Population (2023) |
|---|---|
| White | 84.58% |
| African American | 5.94% |
| Hispanic | 4.03% |
| Asian | 4.61% |
| Native American | 0.84% |
| Hawaiin/Pacific Islander | 0% |
| Race/Ethnicity | Percentage of Public School Students (2023) |
|---|---|
| White | 84.63% |
| African American | 1.3% |
| Hispanic | 6.13% |
| Asian | 3.11% |
| Native American | 0.23% |
| Hawaiin/Pacific Islander | 0.09% |