41 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Moline | 1 | 41,343 | 42,897 | -0.75% | 2,468 | 16.75 | City |
| South Moline township | 2 | 35,607 | 36,573 | -0.21% | 2,235 | 15.93 | Township |
| Rock Island | 3 | 35,540 | 37,019 | -0.83% | 2,107 | 16.87 | City |
| Moline township | 4 | 22,226 | 22,851 | -0.22% | 3,446 | 6.45 | Township |
| Hampton township | 5 | 21,267 | 21,710 | -0.13% | 622 | 34.18 | Township |
| East Moline | 6 | 20,462 | 21,322 | -0.83% | 1,402 | 14.60 | City |
| South Rock Island township | 7 | 17,806 | 18,408 | -0.4% | 2,583 | 6.89 | Township |
| Rock Island township | 8 | 15,546 | 16,032 | -0.38% | 3,255 | 4.78 | Township |
| Blackhawk township | 9 | 9,267 | 9,530 | -0.28% | 331 | 27.99 | Township |
| Silvis | 10 | 7,832 | 7,991 | -0.41% | 1,828 | 4.29 | City |
| Milan | 11 | 4,888 | 5,088 | -0.81% | 781 | 6.25 | Village |
| Coal Valley township | 12 | 4,381 | 4,446 | -0.05% | 372 | 11.78 | Township |
| Coal Valley | 13 | 3,784 | 3,864 | -0.42% | 1,195 | 3.17 | Village |
| Bowling township | 14 | 3,300 | 3,362 | -0.03% | 89 | 36.88 | Township |
| Andalusia township | 15 | 2,222 | 2,265 | 0% | 174 | 12.81 | Township |
| Carbon Cliff | 16 | 1,759 | 1,841 | -0.9% | 840 | 2.10 | Village |
| Coe township | 17 | 1,742 | 1,779 | -0.11% | 48 | 35.93 | Township |
| Hampton | 18 | 1,714 | 1,774 | -0.7% | 1,173 | 1.46 | Village |
| Port Byron | 19 | 1,602 | 1,664 | -0.74% | 660 | 2.43 | Village |
| Edgington township | 20 | 1,385 | 1,424 | -0.22% | 39 | 35.68 | Township |
| Port Byron township | 21 | 1,345 | 1,388 | -0.37% | 380 | 3.54 | Township |
| Andalusia | 22 | 1,144 | 1,181 | -0.61% | 974 | 1.18 | Village |
| Rural township | 23 | 985 | 1,004 | 0% | 27 | 36.21 | Township |
| Rapids City | 24 | 924 | 958 | -0.75% | 568 | 1.63 | Village |
| Cordova township | 25 | 835 | 861 | -0.24% | 34 | 24.68 | Township |
| Drury township | 26 | 736 | 755 | -0.27% | 15 | 49.43 | Township |
| Buffalo Prairie township | 27 | 699 | 711 | 0% | 15 | 46.15 | Township |
| Zuma township | 28 | 660 | 672 | 0% | 28 | 23.76 | Township |
| Cordova | 29 | 644 | 674 | -0.92% | 1,122 | 0.57 | Village |
| Canoe Creek township | 30 | 581 | 589 | 0.17% | 40 | 14.44 | Township |
| Campbell's Island | 31 | 521 | 343 | 7.2% | 1,148 | 0.45 | CDP |
| Edgington | 32 | 519 | 195 | 7.23% | 513 | 1.01 | CDP |
| Reynolds | 33 | 474 | 499 | -1.04% | 1,288 | 0.37 | Village |
| Rock Island Arsenal | 34 | 431 | 353 | 4.36% | 274 | 1.57 | CDP |
| Hillsdale | 35 | 403 | 413 | -0.49% | 622 | 0.65 | Village |
| Milan township | 36 | 300 | 315 | -1.32% | 9 | 35.20 | Township |
| Reynolds township | 37 | 261 | 271 | -1.14% | 7 | 35.44 | Township |
| Taylor Ridge | 38 | 164 | 142 | 7.19% | 106 | 1.55 | CDP |
| Barstow | 39 | 81 | 73 | 6.58% | 764 | 0.11 | CDP |
| Joslin | 40 | 74 | 30 | 7.25% | 16 | 4.64 | CDP |
| Illinois City | 41 | 46 | 58 | 6.98% | 101 | 0.46 | CDP |
Moline is the largest city in Rock Island County, with a population of 41,343.
Illinois City is the smallest city in Rock Island County.
There are 41 cities in Rock Island County, Illinois.