8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oskaloosa | 1 | 1,060 | 1,098 | -0.56% | 1,066 | 1 | City |
| Valley Falls | 2 | 1,053 | 1,091 | -0.57% | 1,496 | 1 | City |
| Perry | 3 | 844 | 849 | -0.12% | 1,127 | 1 | City |
| McLouth | 4 | 827 | 859 | -0.6% | 1,436 | 1 | City |
| Meriden | 5 | 707 | 743 | -0.84% | 919 | 1 | City |
| Ozawkie | 6 | 617 | 635 | -0.48% | 2,077 | 0 | City |
| Nortonville | 7 | 578 | 601 | -0.69% | 1,338 | 0 | City |
| Winchester | 8 | 438 | 453 | -0.45% | 1,331 | 0 | City |
Oskaloosa is the largest city in Jefferson County, with a population of 1,060.
Winchester is the smallest city in Jefferson County, with a population of 438.
There are 8 cities in Jefferson County, Kansas.