Founded in 1831, Rock Island County is one of 102 counties in the state of Illinois. Historically, Rock Island County was formed from Jo Daviess County. The city of Rock Island is the county seat. With FIPS code of 161, Rock Island County has a population of 142,909 and area of 427 square miles (1,106 km2).
List of all cities in Rock Island County, IL alphabetically
| City/Town | Postal Code | Area Code |
| Andalusia, IL | 61232 | 309 |
| Babcock, IL | 61244 | 309 |
| Barstow, IL | 61236 | 309 |
| Buffalo Prairie, IL | 61237 | 309 |
| Byron Hills, IL | 61275 | 309 |
| Campbells Island, IL | 61244 | 309 |
| Carbon Cliff, IL | 61239 | 309 |
| Coal Valley, IL | 61240 | 309 |
| Coe, IL | 61275 | 309 |
| Cordova, IL | 61242 | 309 |
| East Moline, IL | 61244 | 309 |
| Hampton, IL | 61256 | 309 |
| Hillsdale, IL | 61257 | 309 |
| Illinois City, IL | 61259 | 309 |
| Marston, IL | 61279 | 309 |
| Meersman, IL | 61244 | 309 |
| Merry Oaks, IL | 61244 | 309 |
| Milan, IL | 61264 | 309 |
| Mobet Meadows, IL | 61275 | 309 |
| Moline, IL | 61265 | 309 |
| 61266 | 309 | |
| Perryton, IL | 61279 | 309 |
| Port Byron, IL | 61275 | 309 |
| Quad City Airport, IL | 61265 | 309 |
| Rapids City, IL | 61278 | 309 |
| Reynolds, IL | 61279 | 309 |
| Rock Island, IL | 61201 | 309 |
| 61204 | 309 | |
| 61299 | 309 | |
| Rock Island Arsonal, IL | 61299 | 309 |
| Silvis, IL | 61282 | 309 |
| South Moline, IL | 61244 | 309 |
| Taylor Ridge, IL | 61284 | 309 |
| Watertown, IL | 61244 | 309 |
| Whites Addition, IL | 61244 | 309 |