| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Pell City | 1 | 14,600 | 12,973 | 1.96% | 584 | 25 | City |
| Moody | 2 | 13,652 | 13,229 | 0.69% | 557 | 25 | City |
| Margaret | 3 | 7,523 | 5,238 | 5.23% | 766 | 10 | Town |
| Odenville | 4 | 6,208 | 4,932 | 3.07% | 445 | 14 | City |
| Springville | 5 | 5,748 | 4,801 | 2.7% | 598 | 10 | City |
| Argo | 6 | 4,373 | 4,402 | -0.07% | 399 | 11 | City |
| Ashville | 7 | 2,424 | 2,359 | 0.5% | 126 | 19 | City |
| Riverside | 8 | 2,331 | 2,232 | 0.82% | 269 | 9 | City |
| Ragland | 9 | 1,715 | 1,690 | 0.29% | 102 | 17 | Town |
| Steele | 10 | 1,006 | 995 | 0.2% | 150 | 7 | Town |
Pell City is the largest city in St. Clair County, with a population of 14,600.
Steele is the smallest city in St. Clair County, with a population of 1,006.
There are 10 cities in St. Clair County, Alabama.