| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Liberty | 1 | 1,955 | 2,043 | -0.61% | 2,484 | 1 | Town |
| West College Corner | 2 | 508 | 527 | -0.59% | 1,903 | 0 | Town |
| Spring Grove | 3 | 335 | 334 | 0% | 1,102 | 0 | Town |
| Whitewater | 4 | 70 | 71 | 0% | 886 | 0 | Town |
Liberty is the largest city in Union County, with a population of 1,955.
Whitewater is the smallest city in Union County, with a population of 70.
There are 4 cities in Union County, Indiana.