Formed January 1, 1825 (40th county)
Warren County (16,840), Monmouth (8,904)
The classic Richardsonian Romanesque red stone courthouse in Monmouth was built in 1894. It is located in the city square at Main, Archer, A and Broadway streets. O. W. Marble is the building architect. The outside features veteran memorials and canons. Warren County was organized on January 1, 1825 out of Pike County as the 40th county. Oquawaka was the first county seat until 1831 when Monmouth assumed that role. Henderson County was later cut from this county. Revolutionary War hero Joseph Warren is the source name for the county. The county seat is named for the Revolutionary War battle in New Jersey.
Warren County government consists of a sheriff, an attorney, a coroner, a clerk, a treasurer, and an assessor (executive). It has 14 Board Members (legislative.) Fifteen Circuit Court Judges serve Warren, Fulton, Hancock, Henderson, Knox, and McDonough counties and a court clerk serves Warren County (judicial.) The county is in western Illinois. Peoria, Illinois is southeast and Davenport, Iowa is north of the county. The county center is 4.1 miles Southeast of Monmouth. The county is surrounded clockwise by Mercer, Knox, Fulton, McDonough, and Henderson counties.
The area of the county is 542 square miles. It is 47 out of 102 in the state. It ranks 63 out of 102 in population in the state. It has a density of 31.1 persons per square mile making it 71 out of 102 in the state. Warren County has 66.6% of its population in its incorporated areas. United States Highway 34 crosses the county east to west from Knox County to Henderson County. United States Highway 67 goes north to south from Mercer County to McDonough County. The county is a rectangle. Monmouth is in the northern third of the county. Monmouth is the county seat and the largest city. It is 52.9% of the county population. This county is in the Galesburg Micropolitan Statistical Area.
Kirkwood
Little York
Monmouth
Roseville
Alexis
Avon