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Will County, Illinois facts for kids

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Will County
Map of Illinois highlighting Will County
Location within the U.S. state of Illinois
Map of the United States highlighting Illinois
Illinois's location within the U.S.
Country  United States
State  Illinois
Founded January 12, 1836
Seat Joliet
Largest city Joliet
 • Total 849 sq mi (2,200 km2)
 • Land 837 sq mi (2,170 km2)
 • Water 12 sq mi (30 km2)  1.5%%
 • Estimate 
 • Density 810/sq mi (310/km2)
Time zone UTC−6 (Central)
 • Summer (DST) UTC−5 (CDT)
Congressional districts 1st, 2nd, 3rd, 11th, 14th, 16th

Will County is a county located in the northern part of the state of Illinois. According to the 2010 census, it had a population of 677,560, which is an increase of 34.9% from 502,266 in 2000, making it the fourth-most populous county in Illinois. The county seat is Joliet.

Will County is one of the five collar counties of the Chicago-Naperville-Elgin, IL-IN-WI Metropolitan Statistical Area. The portion of Will County around Joliet uses the 815 and 779 area codes, 630 and 331 area code for far northern Will County, and 708 area code for eastern Will County.


Will County was formed in 1836 out of Cook and Iroquois. It was named after Dr. Conrad Will, a businessman involved in salt production in southern Illinois, and also a politician. Will was a member of the first Illinois Constitutional Convention and a member of the Illinois Legislature until his death in 1835. On January 12, 1836, Will County was formed from Cook County and Iroquois County. It included besides its present area, the part of Kankakee County, Illinois lying north of the Kankakee River. Will County lost that area when Kankakee County was organized in 1852, but since then its boundaries have been unchanged.

Thirty-six locations in Will County are listed on the National Register of Historic Places.

"WILL, a county in the E. N. E. part of Illinois, bordering on Indiana, has an area of 1,236 square miles (3,200 km2). It is intersected by the Kankakee and Des Plaines Rivers, branches of the Illinois. The surface is generally level, and destitute of timber, excepting small groves. The soil is very fertile, and much of it is under cultivation. The soil of the prairies is a deep, sandy loam, adapted to Indian corn and grass. In 1850 the county produced 527,903 bushels of Indian corn; 230,885 of wheat; 334,360 of oats; 32,043 tons of hay, and 319,054 pounds of butter. It contained 14 churches, 3 newspaper offices; 3472 pupils attending public schools, and 200 attending other schools. Quarries of building stone are worked near the county seat. The Des Plaines river furnishes water-power. The county is intersected by the Illinois and Michigan canal, by the Chicago branch of the Central railroad, the Chicago and Mississippi, and by the Chicago and Rock Island railroad. Named in honor of Conrad Will, for many years a member of the Illinois legislature. Capital, Joliet. Population, 16,703."

1854 U.S. Gazetteer


According to the U.S. Census Bureau, the county has a total area of 849 square miles (2,200 km2), of which 837 square miles (2,170 km2) is land and 12 square miles (31 km2) (1.5%) is water.

The Kankakee River, Du Page River and the Des Plaines River run through the county and join on its western border. The Illinois and Michigan Canal and the Chicago Sanitary and Ship Canal run through Will County.

A number of areas are preserved as parks (over 20,000 acres (81 km2) total) under the Forest Preserve District of Will County. The 17,000 acres (69 km2) Midewin National Tallgrass Prairie is a U.S. Forest Service park in the county on the grounds of the former Joliet Arsenal. Other parks include Channahon State Park and the Des Plaines Fish and Wildlife Area.

Climate and weather

Weather chart for Joliet, Illinois
temperatures in °F
precipitation totals in inches
source: The Weather Channel

In recent years, average temperatures in the county seat of Joliet have ranged from a low of 13 °F (−11 °C) in January to a high of 85 °F (29 °C) in July, although a record low of −26 °F (−32 °C) was recorded in January 1985 and a record high of 104 °F (40 °C) was recorded in June 1988. Average monthly precipitation ranged from 1.58 inches (40 mm) in January to 4.34 inches (110 mm) in July.

Adjacent counties


Historical population
Census Pop.
1840 10,167
1850 16,703 64.3%
1860 29,321 75.5%
1870 43,013 46.7%
1880 53,422 24.2%
1890 62,007 16.1%
1900 74,764 20.6%
1910 84,371 12.8%
1920 92,911 10.1%
1930 110,732 19.2%
1940 114,210 3.1%
1950 134,336 17.6%
1960 191,617 42.6%
1970 249,498 30.2%
1980 324,460 30.0%
1990 357,313 10.1%
2000 502,266 40.6%
2010 677,560 34.9%
Est. 2016 689,529 1.8%
U.S. Decennial Census
1790–1960 1900–1990
1990–2000 2010–2013

As of the 2010 United States Census, there were 677,560 people, 225,256 households, and 174,062 families residing in the county. The population density was 809.6 inhabitants per square mile (312.6/km2). There were 237,501 housing units at an average density of 283.8 per square mile (109.6/km2). The racial makeup of the county was 76.0% white, 11.2% black or African American, 4.6% Asian, 0.3% American Indian, 5.8% from other races, and 2.3% from two or more races. Those of Hispanic or Latino origin made up 15.6% of the population. In terms of ancestry, 21.6% were German, 18.6% were Irish, 13.3% were Polish, 11.1% were Italian, 5.9% were English, and 2.1% were American.

Of the 225,256 households, 44.0% had children under the age of 18 living with them, 61.9% were married couples living together, 10.9% had a female householder with no husband present, 22.7% were non-families, and 18.5% of all households were made up of individuals. The average household size was 2.97 and the average family size was 3.41. The median age was 35.4 years.

The median income for a household in the county was $75,906 and the median income for a family was $85,488. Males had a median income of $60,867 versus $40,643 for females. The per capita income for the county was $29,811. About 5.0% of families and 6.6% of the population were below the poverty line, including 9.0% of those under age 18 and 5.6% of those age 65 or over.


Will County is served by 4 US Interstate Highways, 4 US Highways, and 12 Illinois Highways.

Major highways

  • I-55.svg Interstate 55
  • I-57.svg Interstate 57
  • I-80.svg Interstate 80
  • I-355.svg Interstate 355
  • US 6.svg U.S. Route 6
  • US 30.svg U.S. Highway 30
  • US 45.svg U.S. Highway 45
  • US 52.svg U.S. Highway 52
  • Illinois 1.svg Illinois Route 1
  • Illinois 7.svg Illinois Route 7
  • Illinois 43.svg Illinois Route 43
  • Illinois 50.svg Illinois Route 50
  • Illinois 53.svg Illinois Route 53
  • Illinois 59.svg Illinois Route 59
  • Illinois 102.svg Illinois Route 102
  • Illinois 113.svg Illinois Route 113
  • Illinois 126.svg Illinois Route 126
  • Illinois 129.svg Illinois Route 129
  • Illinois 171.svg Illinois Route 171
  • Illinois 394.svg Illinois Route 394


Four different Metra commuter rail lines (Metra Electric Main Line, Southwest Service, Rock Island District and Heritage Corridor) connect the parts of the county with the Chicago Loop.

Energy Infrastructure


The county is a major hub in the United States natural gas pipeline grid where pipelines from Canada and the Gulf of Mexico meet and then fan out to serve the Midwest. The following major energy companies own pipeline that run through Will County:

  • Alliance Pipeline
  • Enbridge
  • Integrys Energy Group
    • Peoples Gas
  • Kinder Morgan Interstate Gas Transmission
  • TransCanada
    • ANR Pipeline - Fully owned & operated
    • Northern Border Pipeline - Partially owned & fully operated
  • Vector Pipeline

Joliet Refinery

ExxonMobil owns and operated the Joliet Refinery which is located along the Des Plaines River just east of I-55. According to ExxonMobil, the refinery employs about 600 people and was constructed in 1972.




Census-designated places


Will County is divided into these townships:

  • Channahon
  • Crete
  • Custer
  • DuPage
  • Florence
  • Frankfort
  • Green Garden
  • Homer
  • Jackson
  • Joliet
  • Lockport
  • Manhattan
  • Monee
  • New Lenox
  • Peotone
  • Plainfield
  • Reed
  • Troy
  • Washington
  • Wesley
  • Wheatland
  • Will
  • Wilmington
  • Wilton
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