14 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 |
| Rock Island | 2 | 36,146 | 37,010 | -0.4% | 2,061 | 18 | City |
| East Moline | 3 | 20,836 | 21,313 | -0.38% | 1,428 | 15 | City |
| Silvis | 4 | 8,006 | 7,997 | 0.02% | 1,868 | 4 | City |
| Milan | 5 | 5,002 | 5,094 | -0.3% | 800 | 6 | Village |
| Coal Valley | 6 | 3,886 | 3,876 | 0.05% | 1,227 | 3 | Village |
| Carbon Cliff | 7 | 1,794 | 1,836 | -0.39% | 856 | 2 | Village |
| Hampton | 8 | 1,744 | 1,776 | -0.29% | 1,194 | 1 | Village |
| Port Byron | 9 | 1,632 | 1,665 | -0.31% | 672 | 2 | Village |
| Andalusia | 10 | 1,162 | 1,177 | -0.17% | 989 | 1 | Village |
| Rapids City | 11 | 930 | 944 | -0.21% | 572 | 2 | Village |
| Cordova | 12 | 657 | 674 | -0.45% | 1,145 | 1 | Village |
| Reynolds | 13 | 482 | 499 | -0.62% | 1,310 | 0 | Village |
| Hillsdale | 14 | 412 | 414 | 0% | 636 | 1 | Village |
Moline is the largest city in Rock Island County, with a population of 42,217.
Hillsdale is the smallest city in Rock Island County, with a population of 412.
There are 14 cities in Rock Island County, Illinois.