| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hampton | 1 | 4,262 | 4,323 | -0.05% | 963 | 4 | City |
| Sheffield | 2 | 1,102 | 1,118 | -0.09% | 198 | 6 | City |
| Latimer | 3 | 469 | 478 | -0.21% | 195 | 2 | City |
| Coulter | 4 | 215 | 218 | 0% | 87 | 2 | City |
| Alexander | 5 | 162 | 167 | -0.61% | 38 | 4 | City |
| Geneva | 6 | 134 | 135 | 0% | 328 | 0 | City |
| Hansell | 7 | 83 | 84 | 0% | 369 | 0 | City |
| Popejoy | 8 | 75 | 76 | 0% | 100 | 1 | City |
| Owasa | 9 | 29 | 31 | -3.33% | 52 | 1 | City |
Hampton is the largest city in Franklin County, with a population of 4,262.
Owasa is the smallest city in Franklin County, with a population of 29.
There are 9 cities in Franklin County, Iowa.