9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hampton | 1 | 4,342 | 4,329 | 0.05% | 981 | 4 | City |
| Sheffield | 2 | 1,123 | 1,123 | 0% | 202 | 6 | City |
| Latimer | 3 | 477 | 477 | 0% | 198 | 2 | City |
| Coulter | 4 | 220 | 219 | 0% | 89 | 2 | City |
| Alexander | 5 | 164 | 166 | -0.61% | 38 | 4 | City |
| Geneva | 6 | 137 | 136 | 0% | 335 | 0 | City |
| Hansell | 7 | 85 | 84 | 0% | 378 | 0 | City |
| Popejoy | 8 | 76 | 75 | 0% | 101 | 1 | City |
| Owasa | 9 | 29 | 31 | -3.33% | 52 | 1 | City |
Hampton is the largest city in Franklin County, with a population of 4,342.
Owasa is the smallest city in Franklin County, with a population of 29.
There are 9 cities in Franklin County, Iowa.