| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Gallipolis | 1 | 3,315 | 3,321 | -0.09% | 922 | 4 | Village |
| Rio Grande | 2 | 838 | 724 | 0.12% | 609 | 1 | Village |
| Crown City | 3 | 418 | 422 | -0.24% | 360 | 1 | Village |
| Vinton | 4 | 223 | 225 | -0.45% | 189 | 1 | Village |
| Cheshire | 5 | 122 | 125 | -0.81% | 158 | 1 | Village |
| Centerville (Thurman) | 6 | 86 | 88 | -1.15% | 860 | 0 | Village |
Gallipolis is the largest city in Gallia County, with a population of 3,315.
Centerville (Thurman) is the smallest city in Gallia County, with a population of 86.
There are 6 cities in Gallia County, Ohio.