19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Harrison | 1 | 13,566 | 13,475 | -0.09% | 134 | 101 | Township |
| Jackson | 2 | 6,012 | 5,979 | -0.12% | 166 | 36 | Township |
| Morgan | 3 | 4,061 | 4,021 | -0.02% | 114 | 36 | Township |
| Corydon | 4 | 3,153 | 3,152 | 0% | 1,909 | 2 | Town |
| Posey | 5 | 2,873 | 2,840 | 0.03% | 72 | 40 | Township |
| Blue River | 6 | 2,004 | 1,992 | -0.05% | 52 | 38 | Township |
| Palmyra | 7 | 1,470 | 1,489 | -0.54% | 39 | 37 | Township |
| Boone | 8 | 1,310 | 1,308 | -0.15% | 28 | 47 | Township |
| Heth | 9 | 1,184 | 1,168 | 0.17% | 35 | 34 | Township |
| Lanesville | 10 | 940 | 935 | 0.11% | 999 | 1 | Town |
| Palmyra | 11 | 906 | 901 | 0.11% | 758 | 1 | Town |
| Taylor | 12 | 769 | 766 | -0.26% | 27 | 28 | Township |
| New Salisbury | 13 | 462 | 613 | -2.12% | 234 | 2 | CDP |
| Elizabeth | 14 | 201 | 201 | 0% | 770 | 0 | Town |
| Crandall | 15 | 138 | 136 | 0% | 1,327 | 0 | Town |
| New Middletown | 16 | 89 | 89 | 0% | 2,543 | 0 | Town |
| Laconia | 17 | 74 | 74 | 0% | 1,451 | 0 | Town |
| Mauckport | 18 | 45 | 45 | 0% | 225 | 0 | Town |
| New Amsterdam | 19 | 16 | 15 | 0% | 211 | 0 | Town |
Harrison is the largest city in Harrison County, with a population of 13,566.
New Amsterdam is the smallest city in Harrison County, with a population of 16.
There are 19 cities in Harrison County, Indiana.