Rock Island County, Illinois
County seat: Rock Island · Population 141,869 (2025) · 428 sq mi
Rock Island County is the 15th most populous of Illinois's 102 counties, with 141,869 people (2025 estimate). Its county seat is Rock Island. It is part of the Northwest region, one of the 10 Illinois economic development regions (DCEO). The map shows its 15 cities and towns and the 7 neighboring counties.
Rock Island County facts
- County seat
- Rock Island
- Population (2025 estimate)
- 141,869 −1.9% since 2020
- Land area
- 428 sq mi 67th largest of 102
- Water area
- 24 sq mi
- Population density
- 332 per sq mi
- Established
- 1831
- Named after
- Rock Island Arsenal army post located on Arsenal Island on the Mississippi River
- Largest city
- Moline 42,362
- Median household income
- $67,159
- Cities and towns
- 15 plus 9 CDPs
- ZIP codes
- 21
- Time zone
- Central
- FIPS code
- 17161
Cities and towns in Rock Island County
Rock Island County has 15 incorporated cities, towns and villages. Populations count the people living inside Rock Island County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Moline | City | 42,362 | |
| Rock Island (county seat) | City | 36,225 | |
| East Moline | City | 20,453 | |
| Silvis | City | 7,979 | |
| Milan | Village | 5,028 | |
| Coal Valley | Village | 3,691 | Henry County |
| Carbon Cliff | Village | 1,810 | |
| Hampton | Village | 1,751 | |
| Port Byron | Village | 1,638 | |
| Andalusia | Village | 1,175 | |
| Rapids City | Village | 939 | |
| Cordova | Village | 656 | |
| Oak Grove | Village | 476 | |
| Reynolds | Village | 458 | Mercer County |
| Hillsdale | Village | 413 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Coyne Center | 904 | |
| Rock Island Arsenal | 470 | |
| Edgington | 390 | |
| Taylor Ridge | 276 | |
| Campbell's Island | 203 | |
| Illinois City | 73 | |
| Joslin | 56 | |
| Barstow | 34 | |
| Buffalo Prairie | 9 |
ZIP codes in Rock Island County
21 ZIP codes reach into Rock Island County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 61201
- 61232
- 61236
- 61237
- 61239
- 61240 also Henry County
- 61242
- 61244
- 61256
- 61257
- 61259 also Mercer County
- 61264 also Mercer County
- 61265
- 61272 also Mercer County
- 61273 also Henry and Mercer counties
- 61275
- 61278
- 61279 also Mercer County
- 61281 also Mercer County
- 61282
- 61284
Population of Rock Island County, 2020–2025
Rock Island County shrank by 2,800 people (−1.9%) between April 2020 and July 2025: 734 more deaths than births and a net loss of 2,050 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 144,357 |
| 2021 | 142,485 |
| 2022 | 140,972 |
| 2023 | 140,905 |
| 2024 | 141,591 |
| 2025 | 141,869 |
Neighboring counties
- Scott County, Iowa north · 175,259 people
- Mercer County southwest · 15,229 people
- Henry County east · 48,095 people
- Whiteside County northeast · 54,121 people
- Muscatine County, Iowa west · 41,853 people
- Clinton County, Iowa north · 46,002 people
- Louisa County, Iowa southwest · 10,416 people
Printable Rock Island County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (117 KB)
- PNG (2400 px) (88 KB)
Paste this code to embed the map on your site:
Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
Back to the Illinois county map with all 102 counties. Found an error? Tell us.