21 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cadiz | 1 | 3,209 | 3,392 | -1.08% | 93 | 34 | Township |
| Cadiz | 2 | 2,898 | 3,054 | -0.89% | 330 | 9 | Village |
| Harrisville | 3 | 1,763 | 1,719 | 0.46% | 73 | 24 | Township |
| North | 4 | 1,509 | 1,601 | -1.18% | 65 | 23 | Township |
| Rumley | 5 | 1,213 | 1,277 | -0.98% | 52 | 23 | Township |
| Short Creek | 6 | 961 | 1,016 | -1.13% | 32 | 30 | Township |
| Hopedale | 7 | 886 | 924 | -0.67% | 756 | 1 | Village |
| Freeport | 8 | 697 | 730 | -0.99% | 29 | 24 | Township |
| German | 9 | 693 | 722 | -1% | 28 | 25 | Township |
| Scio | 10 | 634 | 670 | -0.94% | 1,138 | 1 | Village |
| Washington | 11 | 584 | 613 | -0.85% | 19 | 30 | Township |
| Jewett | 12 | 522 | 552 | -0.95% | 1,026 | 1 | Village |
| Stock | 13 | 421 | 443 | -0.94% | 17 | 25 | Township |
| Moorefield | 14 | 381 | 393 | -0.52% | 14 | 27 | Township |
| Bowerston | 15 | 342 | 359 | -0.87% | 676 | 1 | Village |
| Freeport | 16 | 308 | 322 | -0.65% | 514 | 1 | Village |
| Nottingham | 17 | 285 | 303 | -1.38% | 10 | 28 | Township |
| Archer | 18 | 276 | 288 | -0.72% | 11 | 25 | Township |
| New Athens | 19 | 208 | 220 | -0.95% | 722 | 0 | Village |
| Harrisville | 20 | 170 | 178 | -0.58% | 1,118 | 0 | Village |
| Deersville | 21 | 63 | 66 | 0% | 183 | 0 | Village |
Cadiz is the largest city in Harrison County, with a population of 3,209.
Deersville is the smallest city in Harrison County, with a population of 63.
There are 21 cities in Harrison County, Ohio.