| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sullivan | 1 | 4,215 | 4,256 | -0.33% | 2,248 | 2 | City |
| Shelburn | 2 | 1,103 | 1,096 | 0% | 1,596 | 1 | Town |
| Farmersburg | 3 | 1,066 | 1,064 | -0.09% | 1,435 | 1 | Town |
| Dugger | 4 | 796 | 796 | -0.13% | 1,358 | 1 | Town |
| Hymera | 5 | 666 | 656 | 0.15% | 935 | 1 | Town |
| Carlisle | 6 | 619 | 622 | -0.32% | 1,195 | 1 | Town |
| Merom | 7 | 210 | 208 | 0% | 592 | 0 | Town |
Sullivan is the largest city in Sullivan County, with a population of 4,215.
Merom is the smallest city in Sullivan County, with a population of 210.
There are 7 cities in Sullivan County, Indiana.