| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oskaloosa | 1 | 1,052 | 1,096 | -0.75% | 1,058 | 1 | City |
| Valley Falls | 2 | 1,048 | 1,087 | -0.66% | 1,489 | 1 | City |
| Perry | 3 | 847 | 849 | -0.12% | 1,131 | 1 | City |
| McLouth | 4 | 826 | 857 | -0.72% | 1,434 | 1 | City |
| Meriden | 5 | 702 | 738 | -0.99% | 913 | 1 | City |
| Ozawkie | 6 | 613 | 635 | -0.65% | 2,064 | 0 | City |
| Nortonville | 7 | 575 | 602 | -0.69% | 1,331 | 0 | City |
| Winchester | 8 | 436 | 454 | -0.91% | 1,325 | 0 | City |
Oskaloosa is the largest city in Jefferson County, with a population of 1,052.
Winchester is the smallest city in Jefferson County, with a population of 436.
There are 8 cities in Jefferson County, Kansas.