34 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Moline | 1 | 42,217 | 42,891 | -0.26% | 2,520 | 17 | City |
| South Moline | 2 | 36,592 | 36,573 | 0.61% | 2,297 | 16 | Township |
| Rock Island | 3 | 36,146 | 37,010 | -0.4% | 2,061 | 18 | City |
| Moline | 4 | 22,846 | 22,847 | 0.61% | 3,542 | 6 | Township |
| Hampton | 5 | 21,803 | 21,706 | 0.59% | 638 | 34 | Township |
| East Moline | 6 | 20,836 | 21,313 | -0.38% | 1,428 | 15 | City |
| South Rock Island | 7 | 18,264 | 18,410 | 0.41% | 2,649 | 7 | Township |
| Rock Island | 8 | 15,894 | 16,028 | 0.34% | 3,328 | 5 | Township |
| Blackhawk | 9 | 9,545 | 9,532 | 0.59% | 341 | 28 | Township |
| Silvis | 10 | 8,006 | 7,997 | 0.02% | 1,868 | 4 | City |
| Milan | 11 | 5,002 | 5,094 | -0.3% | 800 | 6 | Village |
| Coal Valley | 12 | 4,531 | 4,455 | 0.82% | 385 | 12 | Township |
| Coal Valley | 13 | 3,886 | 3,876 | 0.05% | 1,227 | 3 | Village |
| Bowling | 14 | 3,380 | 3,364 | 0.6% | 92 | 37 | Township |
| Andalusia | 15 | 2,264 | 2,257 | 0.58% | 177 | 13 | Township |
| Carbon Cliff | 16 | 1,794 | 1,836 | -0.39% | 856 | 2 | Village |
| Coe | 17 | 1,785 | 1,777 | 0.62% | 50 | 36 | Township |
| Hampton | 18 | 1,744 | 1,776 | -0.29% | 1,194 | 1 | Village |
| Port Byron | 19 | 1,632 | 1,665 | -0.31% | 672 | 2 | Village |
| Edgington | 20 | 1,422 | 1,427 | 0.49% | 40 | 36 | Township |
| Port Byron | 21 | 1,380 | 1,390 | 0.44% | 390 | 4 | Township |
| Andalusia | 22 | 1,162 | 1,177 | -0.17% | 989 | 1 | Village |
| Rural | 23 | 1,012 | 1,005 | 0.7% | 28 | 36 | Township |
| Rapids City | 24 | 930 | 944 | -0.21% | 572 | 2 | Village |
| Cordova | 25 | 858 | 860 | 0.59% | 35 | 25 | Township |
| Drury | 26 | 761 | 755 | 0.66% | 15 | 49 | Township |
| Buffalo Prairie | 27 | 708 | 712 | 0.28% | 15 | 46 | Township |
| Zuma | 28 | 675 | 671 | 0.6% | 28 | 24 | Township |
| Cordova | 29 | 657 | 674 | -0.45% | 1,145 | 1 | Village |
| Canoe Creek | 30 | 595 | 591 | 0.68% | 41 | 14 | Township |
| Reynolds | 31 | 482 | 499 | -0.62% | 1,310 | 0 | Village |
| Hillsdale | 32 | 412 | 414 | 0% | 636 | 1 | Village |
| Milan | 33 | 309 | 314 | 0% | 9 | 35 | Township |
| Reynolds | 34 | 269 | 271 | 0% | 8 | 35 | Township |
Moline is the largest city in Rock Island County, with a population of 42,217.
Reynolds is the smallest city in Rock Island County, with a population of 269.
There are 34 cities in Rock Island County, Illinois.