Formed January 1, 1825 (37th county)
Peoria County (181,833), Peoria (113,176)
A Modern style concrete building was built in 1965 to serve Peoria County. It replaced an 1878 courthouse also in Peoria, the only county seat. It is located on Main Street between Adams and Jefferson streets. Interstate Highway 74 is two blocks north of the site. Lankton-Ziegele Terry & Associates are the architects. The building was enlarged in 1990. A plaza enhances the back of the building. The county was cut from Fulton County on January 1, 1825 as the 37th county. The county and county seat are named for the Native American tribe.
The area of the county is 618 square miles. It is 33 out of 102 in the state. It ranks 12 out of 102 in population in the state. It has a density of 294.2 persons per square mile making it 12 out of 102 in the state. Peoria County has 80.6% of its population in its incorporated areas. Interstate Highway 74 crosses the county southeast to northwest from Tazewell County to Knox County. United States Highway 24 enters from the east, Tazewell County, and exits to the south, Fulton County. United States Highway 150 parallels Interstate Highway 74 from Tazewell to Knox counties. The county is a triangle with the southwest angle cut away. The City of Peoria is on the central eastern border. Peoria is the county seat and the largest city. It is 62.2% of the county population. The Illinois River forms its eastern border.
Peoria County government consists of a sheriff, an attorney, a coroner, a clerk, a treasurer, and an assessor (executive). It has 18 Board Members (legislative.) Twenty Circuit Court Judges serve Peoria, Marshall, Putnam, Stark, and Tazewell counties and a court clerk serves Peoria County (judicial.) Peoria County is in north central Illinois north of Springfield, Illinois and southwest of Chicago, Illinois. The county center is 12.2 miles West of Peoria nearer Hanna City. The county is surrounded clockwise by Stark, Marshall, Woodford, Tazewell, Fulton, and Knox counties. The county and county seat are pronounced PEE-OER-EE-A. This county is in the Peoria Metropolitan Statistical Area.
Bartonville
Bellevue
Brimfield
Chillicothe
Dunlap
Elmwood
Glasford
Hanna City
Kingston Mines
Mapleton
Norwood
Peoria
Princeville
West Peoria
Farmington
Pekin
Peoria Heights