41 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Moline | 1 | 42,329 | 42,891 | -0.27% | 2,527 | 17 | City |
| South Moline | 2 | 36,371 | 36,573 | 0.61% | 2,283 | 16 | Township |
| Rock Island | 3 | 36,290 | 37,010 | -0.4% | 2,151 | 17 | City |
| Moline | 4 | 22,708 | 22,847 | 0.61% | 3,521 | 6 | Township |
| Hampton | 5 | 21,676 | 21,706 | 0.59% | 634 | 34 | Township |
| East Moline | 6 | 20,915 | 21,313 | -0.38% | 1,433 | 15 | City |
| South Rock Island | 7 | 18,189 | 18,410 | 0.41% | 2,638 | 7 | Township |
| Rock Island | 8 | 15,840 | 16,028 | 0.34% | 3,317 | 5 | Township |
| Blackhawk | 9 | 9,489 | 9,532 | 0.59% | 339 | 28 | Township |
| Silvis | 10 | 8,004 | 7,997 | 0.01% | 1,868 | 4 | City |
| Milan | 11 | 5,017 | 5,094 | -0.32% | 802 | 6 | Village |
| Coal Valley | 12 | 4,494 | 4,455 | 0.83% | 381 | 12 | Township |
| Coal Valley | 13 | 3,884 | 3,876 | 0.03% | 1,227 | 3 | Village |
| Bowling | 14 | 3,360 | 3,364 | 0.6% | 91 | 37 | Township |
| Andalusia | 15 | 2,251 | 2,257 | 0.58% | 176 | 13 | Township |
| Carbon Cliff | 16 | 1,801 | 1,836 | -0.39% | 860 | 2 | Village |
| Coe | 17 | 1,774 | 1,777 | 0.62% | 49 | 36 | Township |
| Hampton | 18 | 1,749 | 1,776 | -0.34% | 1,197 | 1 | Village |
| Port Byron | 19 | 1,637 | 1,665 | -0.37% | 674 | 2 | Village |
| Edgington | 20 | 1,415 | 1,427 | 0.5% | 40 | 36 | Township |
| Port Byron | 21 | 1,374 | 1,390 | 0.44% | 388 | 4 | Township |
| Andalusia | 22 | 1,164 | 1,177 | -0.26% | 991 | 1 | Village |
| Rural | 23 | 1,005 | 1,005 | 0.7% | 28 | 36 | Township |
| Rapids City | 24 | 932 | 944 | -0.32% | 573 | 2 | Village |
| Cordova | 25 | 853 | 860 | 0.59% | 35 | 25 | Township |
| Drury | 26 | 756 | 755 | 0.67% | 15 | 49 | Township |
| Buffalo Prairie | 27 | 706 | 712 | 0.28% | 15 | 46 | Township |
| Zuma | 28 | 671 | 671 | 0.6% | 28 | 24 | Township |
| Cordova | 29 | 660 | 674 | -0.45% | 1,150 | 1 | Village |
| Canoe Creek | 30 | 591 | 591 | 0.68% | 41 | 14 | Township |
| Campbell's Island | 31 | 521 | 343 | 7.2% | 1,148 | 0 | CDP |
| Edgington | 32 | 519 | 195 | 7.23% | 513 | 1 | CDP |
| Reynolds | 33 | 485 | 499 | -0.61% | 1,318 | 0 | Village |
| Rock Island Arsenal | 34 | 431 | 353 | 4.36% | 274 | 2 | CDP |
| Hillsdale | 35 | 412 | 414 | -0.24% | 636 | 1 | Village |
| Milan | 36 | 309 | 314 | 0% | 9 | 35 | Township |
| Reynolds | 37 | 269 | 271 | 0% | 8 | 35 | Township |
| Taylor Ridge | 38 | 164 | 142 | 7.19% | 106 | 2 | CDP |
| Barstow | 39 | 81 | 73 | 6.58% | 764 | 0 | CDP |
| Joslin | 40 | 74 | 30 | 7.25% | 16 | 5 | CDP |
| Illinois City | 41 | 46 | 58 | 6.98% | 101 | 0 | CDP |
Moline is the largest city in Rock Island County, with a population of 42,329.
Illinois City is the smallest city in Rock Island County, with a population of 46.
There are 41 cities in Rock Island County, Illinois.