|Warren County Illinois Cities/Towns -
Berwick, Cameron, Coldbrook, Gerlaw, Greenbush, Kirkwood, Little York, Monmouth (County Seat), Roseville, Smithshire, Swan Creek
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Warren County is a county located in the U.S. state of Illinois. As of 2016, the population was 17,378. Its county seat is Monmouth.
Warren County was organized in 1825. Warren County was named for Dr. Joseph Warren, killed at the Battle of Bunker Hill in 1775. He is believed to have been the first officer to fall in the Revolutionary War.