4 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lake Butler | 1 | 18,356 | 17,700 | 1.08% | 1,610 | 11.40 | CDP |
| Lake Butler | 2 | 2,037 | 1,982 | 0.54% | 864 | 2.36 | City |
| Worthington Springs | 3 | 396 | 378 | 1.02% | 413 | 0.96 | Town |
| Raiford | 4 | 229 | 219 | 0.88% | 420 | 0.55 | Town |
Lake Butler is the largest city in Union County, with a population of 18,356.
Raiford is the smallest city in Union County.
There are 4 cities in Union County, Florida.