| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Moline | 1 | 42,204 | 42,864 | -0.37% | 2,519 | 17 | City |
| Rock Island | 2 | 36,034 | 37,006 | -0.53% | 2,055 | 18 | City |
| East Moline | 3 | 20,229 | 21,301 | -1.1% | 1,386 | 15 | City |
| Silvis | 4 | 7,973 | 7,979 | -0.08% | 1,861 | 4 | City |
| Milan | 5 | 5,009 | 5,093 | -0.38% | 801 | 6 | Village |
| Coal Valley | 6 | 3,855 | 3,868 | -0.1% | 1,218 | 3 | Village |
| Carbon Cliff | 7 | 1,801 | 1,842 | -0.5% | 860 | 2 | Village |
| Hampton | 8 | 1,743 | 1,773 | -0.46% | 1,193 | 1 | Village |
| Port Byron | 9 | 1,631 | 1,662 | -0.43% | 672 | 2 | Village |
| Andalusia | 10 | 1,171 | 1,187 | -0.34% | 997 | 1 | Village |
| Rapids City | 11 | 936 | 945 | -0.32% | 576 | 2 | Village |
| Cordova | 12 | 652 | 669 | -0.61% | 1,136 | 1 | Village |
| Reynolds | 13 | 491 | 508 | -0.81% | 1,334 | 0 | Village |
| Hillsdale | 14 | 411 | 418 | -0.48% | 634 | 1 | Village |
Moline is the largest city in Rock Island County, with a population of 42,204.
Hillsdale is the smallest city in Rock Island County, with a population of 411.
There are 14 cities in Rock Island County, Illinois.