10 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Pell City | 1 | 14,654 | 12,973 | 1.95% | 586 | 25 | City |
| Moody | 2 | 13,781 | 13,226 | 0.68% | 562 | 25 | City |
| Margaret | 3 | 7,385 | 5,192 | 5.21% | 752 | 10 | Town |
| Odenville | 4 | 6,087 | 4,959 | 3.19% | 436 | 14 | City |
| Springville | 5 | 5,686 | 4,803 | 2.65% | 591 | 10 | City |
| Argo | 6 | 4,356 | 4,395 | -0.14% | 397 | 11 | City |
| Ashville | 7 | 2,426 | 2,354 | 0.5% | 126 | 19 | City |
| Riverside | 8 | 2,344 | 2,224 | 0.86% | 271 | 9 | City |
| Ragland | 9 | 1,718 | 1,690 | 0.29% | 102 | 17 | Town |
| Steele | 10 | 1,008 | 992 | 0.3% | 150 | 7 | Town |
Pell City is the largest city in St. Clair County, with a population of 14,654.
Steele is the smallest city in St. Clair County, with a population of 1,008.
There are 10 cities in St. Clair County, Alabama.