Grundy County, Illinois

Grundy County is a county in Illinois, United States, roughly an hour southwest of Chicago via
Interstate 80. It had a population of 52,533 at the 2020 census, an estimated 54,052 by 2025, and
covers 430 square miles (1,100 km2) centred near 41°17′N 88°26′W.

Morris is the county seat and the county’s largest city; its postal code is 60450. The
county holds 1 city, 15 incorporated villages and 3 unincorporated communities across 17
townships, and it runs on Central Time. Its FIPS code is 17063.

Towns & Villages in Grundy County

Grundy County has 19 named places on record: 1 city and 15 incorporated villages, plus 3
unincorporated communities with no local government of their own. Type column: City ·
seat for Morris, Town for every incorporated village, Unincorp. for the rest.

Four places on this list are villagewide population figures, not Grundy-County-only counts.
Channahon’s 13,383 residents are mostly in Will County — most of the village sits in
Channahon Township there, with only a corner reaching into Grundy. Dwight lies mainly in
Livingston County, with just a small portion in Grundy. Seneca is almost entirely in LaSalle
County; a 2006 estimate put only 5 of its then 2,087 residents on the Grundy side. Coal City,
Diamond and Godley each straddle the Grundy–Will County line without a published
county-by-county population split, so their table figures above cover the whole village.

Townships

ZIP Codes

• 60450 — Morris (the county’s most populous ZIP)
• 60447 — Minooka
• 60416 — Coal City (also serves Diamond and Carbon Hill)
• 60410 — Channahon
• 60420 — Dwight
• 61360 — Seneca
• 60444 — Mazon
• 60424 — Gardner
• 60407 — Braceville (also serves Godley)
• 60474 — South Wilmington (also serves East Brooklyn)
• 60479 — Verona
• 60437 — Kinsman

Nettle Creek, Wauponsee and Paytonville have no ZIP code of their own; mail there is delivered
under the nearest incorporated village’s code.

Geography

Grundy County sits along the Illinois River in north-central Illinois, where the Grand Prairie
meets the river’s wooded bluffs. Of its 430 square miles, 418 are land and 12 are water,
about 2.9 percent — most of it the Illinois River itself, which crosses the county through
Morris, and the Kankakee River, which joins the Des Plaines River near the county’s eastern
edge to form the Illinois. The Mazon River, a smaller tributary, drains the county’s southern
townships; the fossil-rich shale along Mazon Creek produced Illinois’s state fossil, the Tully
Monster.

Kendall County lies to the north, Will County to the east, Kankakee County to the southeast,
Livingston County to the south, and LaSalle County to the west. Will County, Kankakee County and LaSalle County each have a profile on
this site; Kendall County and Livingston County do not.

Demographics

Grundy County had a population of 52,533 at the 2020 census, and the latest estimate puts the
county near 54,052 residents. Channahon and Minooka, both shared with neighboring counties, and
Morris are the county’s largest communities. Median household income runs $92,235 (2023 ACS,
Data USA), well above Illinois’s statewide figure of $80,306 (2023 ACS). Population density
works out to roughly 126 people per square mile of land, reflecting the county’s position on
the outer edge of the Chicago metropolitan area alongside large rural townships in its south and
west.

Economy & Local Life

Manufacturing employs the most workers in the county, about 3,292 people, followed by health
care and social assistance at 3,215 and retail trade at 3,149 (Data USA, 2024). Lyondell Chemical
Company, about five miles from Morris, is among the county’s larger private employers.
Dresden Generating Station, a nuclear plant three miles from Morris, and two more nuclear stations
within 15 miles supply power to the Chicago area and anchor a sizeable share of the local
energy-sector workforce. Coal City’s economy shifted away from the coal mining that gave the
village its name after the local mines closed, toward manufacturing and jobs commuting to the
Dresden and Braidwood nuclear stations.

History

Illinois’s General Assembly formed Grundy County on 17 February 1841, carving it out of
LaSalle County. It was named for Felix Grundy, a Tennessee senator who served as United States
Attorney General under President Martin Van Buren. Morris, platted the following year, became the
county seat.

On 16 February 1883, floodwater breached the Diamond Mine near what is now the village of
Diamond, killing 72 miners in one of Illinois’s deadliest mining disasters; a monument in
Diamond commemorates the dead. Coal remained the county’s dominant industry into the early
20th century before the mines exhausted their reserves and closed, and South Wilmington, Braceville
and Carbon Hill all trace their founding to that coal boom. On 3 April 1974, Morris became the
first Illinois community struck during that day’s Super Outbreak, though the tornado caused
only minor damage in the city and no injuries.

Getting There

Interstate 80 runs east–west through the county, crossing Illinois Route 47 in Morris.
Interstate 55 passes through the county’s southwestern corner. US Route 6 and Illinois Routes
17, 47, 53 and 113 also cross Grundy County.

• Joliet — northeast via Interstate 80, in neighboring Will County
• Ottawa — west via Interstate 80, in neighboring LaSalle County
• Kankakee — southeast via Illinois Route 47, in neighboring Kankakee County
• Chicago — roughly an hour northeast via Interstate 80

Chicago’s Midway and O’Hare airports, both northeast of the county, are the nearest
major commercial airports. Amtrak trains call at the Dwight station, on the county’s southern
edge, connecting to Chicago and downstate Illinois.

Frequently Asked Questions

Where is Grundy County located?
It sits in north-central Illinois along the Illinois River, roughly an hour southwest of Chicago,
bordered by Kendall, Will, Kankakee, Livingston and LaSalle counties.

What is the population of Grundy County?
52,533 at the 2020 census, with an estimate near 54,052 by 2025.

How big is Grundy County?
430 square miles (1,100 km2), of which 418 square miles are land.

What is the county seat of Grundy County?
Morris is the county seat and the county’s largest city.

How many towns and villages are in Grundy County?
One city, Morris, and 15 incorporated villages, plus the unincorporated communities of Nettle
Creek, Wauponsee and Paytonville.

What ZIP codes does Grundy County use?
60450 for Morris, 60447 for Minooka, 60416 for Coal City, Diamond and Carbon Hill, plus separate
codes for Channahon, Dwight, Seneca, Mazon, Gardner, Braceville, South Wilmington, Verona and
Kinsman.

What is Grundy County known for?
The 1883 Diamond Mine disaster, one of Illinois’s deadliest, and the Mazon Creek fossil beds
that produced the state fossil, the Tully Monster.

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