Peoria County, Illinois

Peoria County is a county in Illinois, United States, about 165 miles southwest of Chicago. It had a population of 181,830 at the 2020 census, an estimated 178,553 by 2025, and covers 631 square miles (1,630 km2) centred near 40°47′N 89°46′W.

Peoria is the county seat and the county’s largest city; its postal code is 61602. The county holds 6 cities, 11 villages and 9 smaller communities across 19 active civil townships — Peoria and West Peoria are administered independently of the township system — and it runs on Central Time. Its FIPS code is 17143.

Towns & Villages in Peoria County

Peoria County has 26 named places on record: 17 incorporated cities and villages, 5 census-designated places (CDPs) and 4 unincorporated communities with no local government of their own. CDP stands for census designated place; Unincorp. covers crossroads and rural communities with no formal boundary.

Two entries on this list are only partly Peoria County’s. Pekin’s 31,731 residents are counted citywide, but the great majority of the city sits in Tazewell County — only a small annexed strip on its north edge reaches into Peoria County. Farmington works the same way: its 2,389 residents are split across Fulton and Peoria counties, with Peoria County holding the smaller share. Peoria Heights, by contrast, is legally seated in Peoria County alone even though its municipal boundary brushes uninhabited land across Peoria Lake in Woodford County. Kickapoo appears once as an unincorporated crossroads community and once as the township that surrounds it and contains Edwards; the two are not the same place.

Townships

Peoria County has 20 named civil townships; West Peoria Township is now defunct, its territory absorbed into the city of West Peoria and neighboring Limestone Township, leaving 19 active. Peoria itself is coextensive with the independent City of Peoria Township. Population figures below mix census vintages — the Census Bureau published 2020 township counts for only a few of Illinois’s smaller townships, so most rows here carry the 2010 figure, the most recent one on record.

ZIP Codes

Peoria itself carries the bulk of the county’s ZIP codes — 61601 through 61607, 61612 through 61615, 61616 (shared with Peoria Heights), 61625, and a long run of box-only and station codes from 61629 through 61656, 29 codes in all for one city. Every other incorporated place runs its own code: 61523 Chillicothe, 61604 West Peoria and Bellevue, 61607 Bartonville, 61525 Dunlap, 61531 Farmington, 61529 Elmwood, 61533 Glasford, 61536 Hanna City and Smithville, 61539 Kingston Mines, 61547 Mapleton and Lake Camelot, 61552 Mossville, 61554 Pekin (Tazewell-administered), 61559 Princeville and 61569 Trivoli. Rome, Norwood, Kickapoo and the unincorporated crossroads of Laura (61451), Edelstein (61526) and Edwards (61528) either share a neighboring town’s code or, in Rome and Norwood’s case, have no ZIP of their own and are served by rural-route delivery out of the nearest post office.

Geography

Peoria County sits in central Illinois on the western side of the Illinois River valley, a landscape of river bluffs and rolling farmland cut by the Spoon River, Kickapoo Creek, Elbow Creek and Copperas Creek. Of its 631 square miles, 619 are land and 11 are water, about 1.8 percent — most of it the Illinois River itself, which widens into Peoria Lake along the county’s eastern edge between Chillicothe and Peoria.

Knox County lies to the northwest, Stark County to the north, Marshall County to the northeast, Woodford County to the east, Tazewell County to the south and Fulton County to the southwest. Marshall County, Woodford County and Tazewell County each have their own page on this site; Knox, Stark and Fulton counties do not currently.

Demographics

Peoria County had a population of 181,830 at the 2020 census, and the latest estimate puts the county near 178,553 residents as of 2025, a decline of roughly 1.8 percent. Peoria is by far the largest city; Chillicothe, at 6,128, is the second-largest community based entirely within the county — Pekin’s citywide figure is larger, but most of Pekin’s population lives across the line in Tazewell County. Median household income in Peoria County runs $65,108 (ACS, 2024), well below Illinois’s statewide figure of $80,306 (2023 ACS). Population density works out to roughly 294 people per square mile of land.

Economy & Local Life

Health care and social assistance employs the most workers in the county, about 17,142 people, followed by manufacturing at 11,877 and retail trade at 8,257. OSF Saint Francis Medical Center, with roughly 13,500 employees, is the county’s single largest employer and one of the largest hospitals in downstate Illinois. Caterpillar Inc., which built its worldwide headquarters in Peoria before relocating it out of state in 2017, still employs around 12,000 people across its Peoria-area manufacturing and engineering operations. Carle Health runs a second major hospital system in the city. Bradley University, founded in 1897 and enrolling about 5,200 students, anchors Peoria’s West Bluff neighborhood. The county’s biggest annual event is the Steamboat Classic, a four-mile road race through downtown Peoria each June that has run since 1974.

History

Peoria County was formed in 1825 out of Fulton County and named for the Peoria, an Illiniwek people who lived along this stretch of the Illinois River. The city of Peoria traces its European roots to 1691, when French explorer Henri de Tonti built a fort here, making it one of the oldest continuously settled sites in Illinois.

On October 16, 1854, Abraham Lincoln delivered his Peoria speech opposing the Kansas–Nebraska Act’s extension of slavery into new territories, a speech historians treat as the opening argument of his political comeback. In 1942, government researchers at the US Department of Agriculture’s Northern Regional Research Laboratory in Peoria isolated a strain of Penicillium mold from a moldy cantaloupe that became the basis for large-scale wartime penicillin production.

Getting There

Interstate 74 and Interstate 474 cross the county through Peoria and its suburbs; US Route 24 and US Route 150 also run through the county, along with Illinois Routes 6, 8, 9, 29, 40, 78, 90, 91 and 116.

• Bloomington-Normal — about 40 miles southeast
• Springfield — about 70 miles south
• Galesburg — about 45 miles west
• Chicago — about 165 miles northeast

General Wayne A. Downing Peoria International Airport, five miles west of downtown Peoria near Bartonville, is the county’s commercial airport. Amtrak has no station in Peoria County; the nearest stop is Uptown Station in Normal, about 40 miles southeast, served by five daily round trips on the Chicago–St. Louis line.

Frequently Asked Questions

Where is Peoria County located?
It sits in central Illinois on the Illinois River, about 165 miles southwest of Chicago, bordered by Knox, Stark, Marshall, Woodford, Tazewell and Fulton counties.

What is the population of Peoria County?
181,830 at the 2020 census, with an estimated 178,553 residents as of 2025.

How big is Peoria County?
631 square miles (1,630 km2), of which 619 square miles are land.

What is the county seat of Peoria County?
Peoria, first settled by the French in 1691, is the county seat and largest city.

How many towns and cities are in Peoria County?
Six cities — Peoria, Pekin (mostly in Tazewell County), Chillicothe, West Peoria, Farmington (partly in Fulton County) and Elmwood — plus 11 villages, 5 census-designated places and 4 unincorporated communities.

What ZIP codes does Peoria County use?
Peoria itself uses 29 codes from 61601 to 61656; other towns run their own, including 61523 Chillicothe, 61525 Dunlap, 61529 Elmwood, 61533 Glasford, 61536 Hanna City, 61539 Kingston Mines, 61559 Princeville and 61569 Trivoli.

What is Peoria County known for?
Abraham Lincoln’s 1854 Peoria speech against the Kansas–Nebraska Act, the 1942 penicillin research breakthrough at Peoria’s USDA lab, and Caterpillar Inc.’s manufacturing roots.

More counties in this state: Towns and villages in Illinois.