18 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Harrison | 1 | 13,554 | 13,475 | -0.09% | 134 | 101 | Township |
| Jackson | 2 | 6,005 | 5,979 | -0.12% | 166 | 36 | Township |
| Morgan | 3 | 4,060 | 4,021 | -0.02% | 114 | 36 | Township |
| Corydon | 4 | 3,153 | 3,152 | 0% | 1,909 | 2 | Town |
| Posey | 5 | 2,874 | 2,840 | 0.03% | 72 | 40 | Township |
| Blue River | 6 | 2,003 | 1,992 | -0.05% | 52 | 38 | Township |
| Palmyra | 7 | 1,462 | 1,489 | -0.54% | 39 | 37 | Township |
| Boone | 8 | 1,308 | 1,308 | -0.15% | 28 | 47 | Township |
| Heth | 9 | 1,186 | 1,168 | 0.17% | 35 | 34 | Township |
| Lanesville | 10 | 941 | 935 | 0.11% | 1,000 | 1 | Town |
| Palmyra | 11 | 907 | 901 | 0.11% | 758 | 1 | Town |
| Taylor | 12 | 767 | 766 | -0.26% | 27 | 28 | Township |
| Elizabeth | 13 | 201 | 201 | 0% | 770 | 0 | Town |
| Crandall | 14 | 139 | 136 | 0.72% | 1,337 | 0 | Town |
| New Middletown | 15 | 89 | 89 | 0% | 2,543 | 0 | Town |
| Laconia | 16 | 74 | 74 | 0% | 1,451 | 0 | Town |
| Mauckport | 17 | 45 | 45 | 0% | 225 | 0 | Town |
| New Amsterdam | 18 | 16 | 15 | 0% | 211 | 0 | Town |
Harrison is the largest city in Harrison County, with a population of 13,554.
New Amsterdam is the smallest city in Harrison County, with a population of 16.
There are 18 cities in Harrison County, Indiana.