8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairfield | 1 | 9,526 | 9,450 | 0.16% | 1,440 | 7 | City |
| Batavia | 2 | 434 | 434 | 0% | 705 | 1 | City |
| Maharishi Vedic City | 3 | 294 | 273 | 1.38% | 88 | 3 | City |
| Libertyville | 4 | 278 | 277 | 0% | 549 | 1 | City |
| Lockridge | 5 | 245 | 242 | 0% | 393 | 1 | City |
| Packwood | 6 | 186 | 186 | 0% | 248 | 1 | City |
| Pleasant Plain | 7 | 83 | 83 | 0% | 82 | 1 | City |
| Coppock | 8 | 34 | 36 | -2.86% | 147 | 0 | City |
Fairfield is the largest city in Jefferson County, with a population of 9,526.
Coppock is the smallest city in Jefferson County, with a population of 34.
There are 8 cities in Jefferson County, Iowa.