|Rock Island County Illinois Cities/Towns -
Andalusia, Carbon Cliff, Coal Valley, Cordova, Coyne Center, East Moline, Edgington, Hampton, Hillsdale, Milan, Moline, Oak Grove, Port Byron, Rapids City, Rock Island (County Seat), Silvis
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Rock Island County is a county located in the U.S. state of Illinois. A 2016 estimate shows a population of 144,784. Its county seat is Rock Island.
Rock Island County was formed in 1831. It was named for Rock Island, an island in the Mississippi River now known as Arsenal Island.