| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sabetha | 1 | 2,459 | 2,541 | -0.61% | 738 | 3 | City |
| Seneca | 2 | 2,140 | 2,129 | 0.05% | 1,197 | 2 | City |
| Centralia | 3 | 487 | 478 | 0.41% | 1,073 | 0 | City |
| Wetmore | 4 | 336 | 350 | -0.59% | 868 | 0 | City |
| Corning | 5 | 204 | 212 | -0.97% | 671 | 0 | City |
| Bern | 6 | 160 | 166 | -0.62% | 563 | 0 | City |
| Wheaton | 7 | 112 | 101 | 1.82% | 727 | 0 | City |
| Goff | 8 | 107 | 106 | 0% | 519 | 0 | City |
| Oneida | 9 | 57 | 60 | -1.72% | 248 | 0 | City |
Sabetha is the largest city in Nemaha County, with a population of 2,459.
Oneida is the smallest city in Nemaha County, with a population of 57.
There are 9 cities in Nemaha County, Kansas.