| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairfield | 1 | 9,181 | 9,445 | -0.42% | 1,388 | 7 | City |
| Batavia | 2 | 416 | 433 | -0.72% | 675 | 1 | City |
| Maharishi Vedic City | 3 | 283 | 272 | 0.71% | 85 | 3 | City |
| Libertyville | 4 | 267 | 277 | -0.74% | 528 | 1 | City |
| Lockridge | 5 | 238 | 243 | -0.42% | 381 | 1 | City |
| Packwood | 6 | 179 | 185 | -0.56% | 239 | 1 | City |
| Pleasant Plain | 7 | 75 | 78 | -1.32% | 74 | 1 | City |
| Coppock | 8 | 34 | 36 | -2.86% | 147 | 0 | City |
Fairfield is the largest city in Jefferson County, with a population of 9,181.
Coppock is the smallest city in Jefferson County, with a population of 34.
There are 8 cities in Jefferson County, Iowa.