| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Vandalia | 1 | 7,041 | 7,434 | -0.94% | 864 | 8 | City |
| St. Elmo | 2 | 1,206 | 1,248 | -0.58% | 813 | 1 | City |
| Ramsey | 3 | 879 | 909 | -0.57% | 791 | 1 | Village |
| Brownstown | 4 | 670 | 692 | -0.59% | 878 | 1 | Village |
| Farina | 5 | 521 | 538 | -0.57% | 358 | 1 | Village |
| St. Peter | 6 | 313 | 326 | -0.63% | 601 | 1 | Village |
| Bingham | 7 | 57 | 62 | -1.72% | 208 | 0 | Village |
Vandalia is the largest city in Fayette County, with a population of 7,041.
Bingham is the smallest city in Fayette County, with a population of 57.
There are 7 cities in Fayette County, Illinois.