8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairfield | 1 | 9,541 | 9,450 | 0.16% | 1,443 | 7 | City |
| Batavia | 2 | 434 | 434 | 0% | 705 | 1 | City |
| Maharishi Vedic City | 3 | 298 | 273 | 1.36% | 89 | 3 | City |
| Libertyville | 4 | 278 | 277 | 0% | 549 | 1 | City |
| Lockridge | 5 | 246 | 242 | 0.41% | 394 | 1 | City |
| Packwood | 6 | 186 | 186 | 0% | 248 | 1 | City |
| Pleasant Plain | 7 | 83 | 83 | 0% | 82 | 1 | City |
| Coppock | 8 | 34 | 36 | 0% | 147 | 0 | City |
Fairfield is the largest city in Jefferson County, with a population of 9,541.
Coppock is the smallest city in Jefferson County, with a population of 34.
There are 8 cities in Jefferson County, Iowa.