| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Macomb | 1 | 14,348 | 15,361 | -1.25% | 1,324 | 11 | City |
| Bushnell | 2 | 2,581 | 2,697 | -0.73% | 1,219 | 2 | City |
| Colchester | 3 | 1,063 | 1,108 | -0.65% | 924 | 1 | City |
| Blandinsville | 4 | 540 | 564 | -0.74% | 617 | 1 | Village |
| Prairie City | 5 | 390 | 405 | -0.51% | 387 | 1 | Village |
| Industry | 6 | 380 | 397 | -0.78% | 826 | 0 | Village |
| Good Hope | 7 | 347 | 360 | -0.57% | 1,157 | 0 | Village |
| Bardolph | 8 | 201 | 209 | -0.99% | 326 | 1 | Village |
| Tennessee | 9 | 97 | 100 | -1.02% | 228 | 0 | Village |
| Sciota | 10 | 31 | 33 | -3.13% | 99 | 0 | Village |
Macomb is the largest city in McDonough County, with a population of 14,348.
Sciota is the smallest city in McDonough County, with a population of 31.
There are 10 cities in McDonough County, Illinois.