| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mount Vernon | 1 | 6,251 | 6,479 | -0.6% | 2,172 | 3 | City |
| Poseyville | 2 | 965 | 969 | -0.1% | 1,496 | 1 | Town |
| New Harmony | 3 | 677 | 693 | -0.44% | 831 | 1 | Town |
| Cynthiana | 4 | 552 | 554 | 0% | 1,383 | 0 | Town |
| Griffin | 5 | 138 | 141 | -0.72% | 2,029 | 0 | Town |
Mount Vernon is the largest city in Posey County, with a population of 6,251.
Griffin is the smallest city in Posey County, with a population of 138.
There are 5 cities in Posey County, Indiana.