10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Effingham | 1 | 12,233 | 12,295 | -0.1% | 1,143 | 10.70 | City |
| Altamont | 2 | 2,168 | 2,217 | -0.46% | 1,411 | 1.54 | City |
| Teutopolis | 3 | 1,687 | 1,626 | 0.72% | 826 | 2.04 | Village |
| Dieterich | 4 | 856 | 891 | -0.81% | 627 | 1.37 | Village |
| Watson | 5 | 651 | 670 | -0.61% | 596 | 1.09 | Village |
| Beecher City | 6 | 415 | 429 | -0.72% | 464 | 0.90 | Village |
| Edgewood | 7 | 386 | 398 | -0.52% | 381 | 1.01 | Village |
| Mason | 8 | 315 | 325 | -0.63% | 245 | 1.29 | Town |
| Montrose | 9 | 207 | 211 | -0.48% | 325 | 0.64 | Village |
| Shumway | 10 | 179 | 184 | -0.56% | 539 | 0.33 | Village |
Effingham is the largest city in Effingham County, with a population of 12,233.
Shumway is the smallest city in Effingham County.
There are 10 cities in Effingham County, Illinois.