List of Interstate Highways in Illinois
This is a list of Interstate Highways in Illinois, all of which are owned and maintained by the U.S. state of Illinois. The Illinois Department of Transportation (IDOT) is responsible for maintaining the Interstate Highways in Illinois. The Interstate Highway System in Illinois consists of twelve primary highways and eleven auxiliary highways which cover 2,169.53 miles (3,491.52 km). The Interstate Highway with the longest section in Illinois is Interstate 57 at 358.57 miles (577.06 km); the shortest Interstate Highway in Illinois is Interstate 190 at 3.07 miles (4.94 km).
Primary Interstate Highways 
|I-24||Williamson, Johnson, and Massac counties||38.73 mi (62.33 km)||I-24 runs from I-57 in rural Williamson County east to the Kentucky border in Metropolis.|
|I-39||McLean, Woodford, Marshall, LaSalle, Lee, Ogle, and Winnebago counties||140.82 mi (226.63 km)||I-39 runs from I-55 in Normal to the Wisconsin border in South Beloit.||1989|||
|I-55||St. Clair, Madison, Macoupin, Montgomery, Sangamon, Logan, McLean, Livingston, Grundy, Will, DuPage, and Cook counties||313.08 mi (503.85 km)||I-55 runs from the Missouri border in East St. Louis to US 41 in Chicago.|
|I-57||Alexander, Pulaski, Union, Johnson, Williamson, Franklin, Jefferson, Marion, Fayette, Effingham, Cumberland, Coles, Douglas, Champaign, Ford, Iroquois, Kankakee, Will, and Cook counties||364.16 mi (586.06 km)||I-57 runs from the Missouri border near Cairo to I-94 in southern Chicago.|
|I-64||St. Clair, Clinton, Washington, Jefferson, Wayne, White||128.12 mi (206.19 km)||I-64 runs from the Missouri state line in East St. Louis to the Indiana state line in Grayville.|
|I-70||St. Clair, Madison, Bond, Fayette, Effingham, Cumberland, and Clark counties||155.94 mi (250.96 km)||I-70 runs from the Missouri state line in East St. Louis to the Indiana state line in Clark County.|
|I-72||Pike, Scott, Morgan, Sangamon, Macon, Piatt, and Champaign counties||182.56 mi (293.80 km)||I-72 runs from the Missouri state line in Pike County to east of I-57 in Champaign.|
|I-74||Rock Island, Henry, Knox, Peoria, Tazewell, Woodford, McLean, De Witt, Piatt, Champaign, and Vermillion counties||220.34 mi (354.60 km)||I-74 runs from the Iowa border in Moline to the Indiana border in Danville.|
|I-80||Rock Island, Henry, Bureau, LaSalle, Grundy, Kendall, Will, and Cook counties||163.52 mi (263.16 km)||I-80 runs from the Iowa border in Rock Island County to the Indiana border in Lansing.|
|I-88||Rock Island, Whiteside, Lee, Ogle, DeKalb, Kane, DuPage, and Cook counties||140.60 mi (226.27 km)||I-88 runs from I-80 in Silvis to I-290 in Hillside.||1987|||
|I-90||Winnebago, Boone, McHenry, Kane, and Cook counties||123.89 mi (199.38 km)||I-90 runs from the Wisconsin state line in South Beloit to the Indiana state line in Chicago.|
|I-94||Lake and Cook counties||78.00 mi (125.53 km)||I-94 runs from the Wisconsin state line north of Wadsworth to the Indiana state line in Lansing|
Auxiliary Interstate Highways 
|I-155||Logan and Tazewell counties||32.13 mi (51.71 km)||I-155 runs from I-55 in Logan County to I-74 in Morton.||1992|||
|I-172||Adams County||19.69 mi (31.69 km)||I-172 runs from I-72 in Fall Creek to US 24 in Fowler.||1995|||
|I-180||Putnam and Bureau counties||13.19 mi (21.23 km)||I-180 runs from IL 71 in Hennepin to I-80 in rural Bureau County.|
|I-190||Cook County||3.07 mi (4.94 km)||I-190 runs from O'Hare International Airport in Chicago to I-90 in Chicago.|
|I-255||Monroe, St. Clair, and Madison counties||27.05 mi (43.53 km)||I-255 runs from the Missouri state line in Columbia to I-270 and IL 255 in Pontoon Beach.|
|I-270||Madison County||14.97 mi (24.09 km)||I-270 runs from the Missouri state line at the New Chain of Rocks Bridge to I-70 in Troy.|
|I-280||Rock Island and Henry counties||8.21 mi (13.21 km)||I-280 runs from the Iowa state line in Rock Island to I-74 and I-80 in Colona.|
|I-290||Cook and DuPage counties||29.84 mi (48.02 km)||I-290 runs from I-90 in Schaumburg to I-90 and I-94 in Chicago.|
|I-294||Cook County||48.10 mi (77.41 km)||I-294 runs from I-94 in Northbrook to I-80 and I-94 in South Holland.|
|I-355||Will, Cook, and DuPage counties||32.5 mi (52.3 km)||I-355 runs from I-80 in New Lenox to I-290 in Itasca.||1989|||
|I-474||Peoria and Tazewell counties||14.88 mi (23.95 km)||I-474 runs from I-74 and IL 6 in Peoria to I-74 in Tazewell County. It serves as a bypass of Peoria.|
- Federal Highway Administration. "Interstate Frequently Asked Questions". Retrieved 2008-02-25.
- "Route Log and Finder List — Interstate Routes in Each of the 50 States, District of Columbia, and Puerto Rico — table 3". Federal Highway Administration. 2002-10-31. Retrieved 2008-03-17.
- I-355 originally ran 20.01 miles (32.20 km) from I-55 to I-290, according to Illinois' 2005 GIS data. The southern extension added 12.5 miles (20.1 km) to this length, according to the Illinois State Toll Highway Authority.
- Zehr, Melinda (1 December 1989). "5-mile section of I-39 to open in 2 weeks". The Pantagraph.
- Mehler, Neil H. (1987-07-06). "Road with many names gets a new one". Chicago Tribune. Retrieved 2008-02-16.
- Smothers, Michael (1992-10-30). "31-mile superhighway opens after 30-year drive for safer road". Peoria Journal-Star.
- American Association of State Highway and Transportation Officials (1995-06-09). "Route Numbering Committee Agenda". Retrieved 2008-04-03.
- Hausner, Les (1989-12-22). "Opening of I-355 will put some zip in Du Page traffic". Chicago Sun Times. Retrieved 2008-01-11.