Rock Island County, Illinois
Rock Island County, Illinois | |
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Rock Island County Justice Center | |
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Logo | |
Location within the U.S. state of Illinois | |
| Coordinates: 41°28′N 90°34′W / 41.47°N 90.57°W | |
| Country | United States |
| State | Illinois |
| Founded | 1831 |
| Named after | Rock (Arsenal) Island |
| Seat | Rock Island |
| Largest city | Moline |
| Area | |
• Total | 451 sq mi (1,170 km2) |
| • Land | 428 sq mi (1,110 km2) |
| • Water | 24 sq mi (62 km2) 5.2% |
| Population (2020) | |
• Total | 144,672 |
• Estimate (2024) | 142,731 |
| • Density | 338/sq mi (131/km2) |
| Time zone | UTC−6 (Central) |
| • Summer (DST) | UTC−5 (CDT) |
| Congressional district | 17th |
| Website | rockislandcountyil |
Rock Island County is a county located in the U.S. state of Illinois, bounded on the west by the Mississippi River. According to the 2020 census, it had a population of 144,672. Its county seat is Rock Island; its largest city is neighboring Moline. Rock Island County is one of the four counties that make up the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.