10 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Effingham | 1 | 12,487 | 12,328 | 0.22% | 1,147 | 11 | City |
| Altamont | 2 | 2,190 | 2,219 | -0.23% | 1,425 | 2 | City |
| Teutopolis | 3 | 1,727 | 1,627 | 0.99% | 845 | 2 | Village |
| Dieterich | 4 | 870 | 896 | -0.46% | 637 | 1 | Village |
| Watson | 5 | 651 | 668 | -0.46% | 596 | 1 | Village |
| Beecher City | 6 | 420 | 429 | -0.24% | 469 | 1 | Village |
| Edgewood | 7 | 389 | 397 | -0.26% | 384 | 1 | Village |
| Mason | 8 | 319 | 325 | -0.31% | 248 | 1 | Town |
| Montrose | 9 | 215 | 217 | 0% | 338 | 1 | Village |
| Shumway | 10 | 185 | 188 | 0% | 557 | 0 | Village |
Effingham is the largest city in Effingham County, with a population of 12,487.
Shumway is the smallest city in Effingham County, with a population of 185.
There are 10 cities in Effingham County, Illinois.