| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cadiz | 1 | 2,939 | 3,055 | -0.71% | 335 | 9 | Village |
| Hopedale | 2 | 886 | 922 | -0.67% | 756 | 1 | Village |
| Scio | 3 | 643 | 673 | -0.92% | 1,154 | 1 | Village |
| Jewett | 4 | 529 | 553 | -0.94% | 1,039 | 1 | Village |
| Bowerston | 5 | 345 | 360 | -1.15% | 682 | 1 | Village |
| Freeport | 6 | 311 | 325 | -0.96% | 519 | 1 | Village |
| New Athens | 7 | 212 | 220 | -0.93% | 736 | 0 | Village |
| Harrisville | 8 | 173 | 180 | -1.14% | 1,138 | 0 | Village |
| Deersville | 9 | 62 | 65 | -1.59% | 180 | 0 | Village |
Cadiz is the largest city in Harrison County, with a population of 2,939.
Deersville is the smallest city in Harrison County, with a population of 62.
There are 9 cities in Harrison County, Ohio.