| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Farmerville | 1 | 3,422 | 3,453 | -0.29% | 592 | 6 | Town |
| Bernice | 2 | 1,297 | 1,356 | -0.61% | 400 | 3 | Town |
| Marion | 3 | 590 | 623 | -0.84% | 184 | 3 | Town |
| Spearsville | 4 | 122 | 129 | -0.81% | 52 | 2 | Village |
| Downsville | 5 | 112 | 121 | -0.88% | 151 | 1 | Village |
| Lillie | 6 | 108 | 110 | -0.92% | 56 | 2 | Village |
Farmerville is the largest city in Union Parish, with a population of 3,422.
Lillie is the smallest city in Union Parish, with a population of 108.
There are 6 cities in Union Parish, Louisiana.