U.S. Route 40 in Illinois

U.S. Route 40
National Road
US 40 highlighted in red
Route information
Maintained by IDOT
Length	159.8 mi[1][2] (257.2 km)
Existed	1926 (1926)–present
Tourist routes	Historic National Road
Major junctions
West end	I-55 / I-64 / US 40 in East St. Louis
Major intersections	I-70 in East St. Louis I-255 in Collinsville I-70 near Highland I-70 near Stubblefield I-70 in Vandalia US 51 in Vandalia I-70 near Brownstown US 45 in Effingham I-70 in Wabash Township
East end	I-70 / US 40 near State Line, IN
Location
Country	United States
State	Illinois
Counties	St. Clair, Madison, Bond, Fayette, Effingham, Cumberland, Clark
Highway system
United States Numbered Highway System List Special Divided Illinois State Highway System Interstate US State Tollways Scenic
← IL 39 → IL 40
← IL 10 IL 11 → US 12

U.S. Route 40 (US 40) runs east–west across south central Illinois for 159.8 miles (257.2 km). US 40 enters the state from Missouri across the Poplar Street Bridge over the Mississippi River at East St. Louis concurrent with Interstate 55 (I-55) and I-64 and exits just south of State Line, Indiana, running concurrently with I-70. For the majority of its route through Illinois, US 40 follows the National Road, including the route's initial western terminus at Vandalia.

For nearly its entire route, US 40 is two-lane and rural, with the exception of portions in and around major towns and cities. For its entire length, US 40 closely aligns with I-70. Not only does the route intersect with the Interstate six times, but also has three concurrencies with the highway; both highways exit into Indiana on the same road.