| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sullivan | 1 | 4,230 | 4,259 | -0.12% | 2,256 | 2 | City |
| Shelburn | 2 | 1,114 | 1,104 | 0.18% | 1,612 | 1 | Town |
| Farmersburg | 3 | 1,065 | 1,068 | 0% | 1,433 | 1 | Town |
| Dugger | 4 | 794 | 796 | 0% | 1,355 | 1 | Town |
| Hymera | 5 | 663 | 656 | 0.15% | 931 | 1 | Town |
| Carlisle | 6 | 612 | 620 | -0.16% | 1,181 | 1 | Town |
| Merom | 7 | 209 | 209 | 0% | 589 | 0 | Town |
Sullivan is the largest city in Sullivan County, with a population of 4,230.
Merom is the smallest city in Sullivan County, with a population of 209.
There are 7 cities in Sullivan County, Indiana.