18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Tuscola township | 1 | 5,388 | 5,452 | -0.3% | 86 | 62.51 | Township |
| Tuscola | 2 | 4,592 | 4,646 | -0.24% | 1,557 | 2.95 | City |
| Bourbon township | 3 | 4,162 | 4,094 | 0.65% | 97 | 43.11 | Township |
| Camargo township | 4 | 3,434 | 3,513 | -0.46% | 89 | 38.59 | Township |
| Arcola township | 5 | 3,200 | 3,277 | -0.59% | 60 | 53.67 | Township |
| Arcola | 6 | 2,864 | 2,929 | -0.45% | 1,416 | 2.02 | City |
| Villa Grove | 7 | 2,412 | 2,482 | -0.58% | 1,606 | 1.50 | City |
| Arthur | 8 | 2,267 | 2,227 | 0.35% | 1,696 | 1.34 | Village |
| Garrett township | 9 | 1,298 | 1,322 | -0.46% | 25 | 52.20 | Township |
| Atwood | 10 | 1,089 | 1,114 | -0.46% | 1,774 | 0.61 | Village |
| Newman township | 11 | 987 | 1,005 | -0.4% | 24 | 40.71 | Township |
| Newman | 12 | 763 | 778 | -0.39% | 1,245 | 0.61 | City |
| Bowdre township | 13 | 615 | 624 | -0.32% | 13 | 48.08 | Township |
| Camargo | 14 | 443 | 452 | -0.45% | 352 | 1.26 | Village |
| Hindsboro | 15 | 267 | 276 | -0.74% | 993 | 0.27 | Village |
| Sargent township | 16 | 246 | 249 | -0.4% | 5 | 46.95 | Township |
| Murdock township | 17 | 223 | 228 | -0.45% | 7 | 30.84 | Township |
| Garrett | 18 | 124 | 124 | 0% | 1,148 | 0.11 | Village |
Tuscola township is the largest city in Douglas County, with a population of 5,388.
Garrett is the smallest city in Douglas County.
There are 18 cities in Douglas County, Illinois.