Illinois Route 203 is a north–south state road in southwestern Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

. It runs from just south of I-55

Interstate 55

Interstate 55 is an Interstate Highway in the central United States. Its odd number indicates that it is a north–south Interstate Highway. I-55 goes from LaPlace, Louisiana at Interstate 10 to Chicago at U.S. Route 41 , at McCormick Place. A common nickname for the highway is "double...

, I-70

Interstate 70

Interstate 70 is an Interstate Highway in the United States that runs from Interstate 15 near Cove Fort, Utah, to a Park and Ride near Baltimore, Maryland. It was the first Interstate Highway project in the United States. I-70 approximately traces the path of U.S. Route 40 east of the Rocky...

, and U.S. 40 around Gateway International Raceway

Gateway International Raceway

Gateway Motorsports Park is a race track in Madison, Illinois, USA, just east of St. Louis, Missouri. After being shuttered by former owner Dover Motorsports Inc., on Nov. 3, 2010, it was announced Sept. 8, 2011, that the facility would re-open and host an NHRA Full Throttle Series event Oct. 5-7,...

 at Collinsville Road (former U.S. 40) in Fairmont City

Fairmont City, Illinois

Fairmont City is a village in St. Clair and Madison Counties, Illinois, United States. The population was 2,436 at the 2000 census. Fairmont City holds the highest percentage of Hispanics in the entire St...

, north to I-270 near Pontoon Beach

Pontoon Beach, Illinois

Pontoon Beach is a village in Madison County, Illinois, United States. The population was 5,620 at the 2000 census.-Geography:Pontoon Beach is located at ....

. This is a distance of 9.51 miles (15.3 km). Illinois 203 is a former segment of U.S. Highway 66.

Route description

Illinois 203 is a major north–south artery through the eastern metropolitan St. Louis

St. Louis, Missouri

St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

 area.

Major intersections

• I-55, I-70, and US-40
• 20th Street
• Illinois Route 162
  Illinois Route 162
  Illinois Route 162 is an east–west highway in southwestern Illinois. It runs from Illinois Route 203 in Granite City east to U.S. Route 40 near Troy. This is a distance of .- Route description :...
  
  
• Madison Avenue
• Pontoon Road
• Maryville Road
• I-270
• Old Alton Road

History

Illinois 203 replaced an older alignment of Illinois Route 3

Illinois Route 3

Illinois Route 3 is a major north–south arterial state highway in southwestern Illinois. It has its southern terminus at Cairo Junction at the intersection of Interstate 57 and U.S. Route 51, and its northern terminus in Grafton at Illinois Route 100...

 in 1964. It originally ran to Hartford

Hartford, Illinois

Hartford is a village in Madison County, Illinois, near the mouth of the Missouri River. The population was 1,545 at the 2000 census. Lewis and Clark spent the winter of 1803-1804 here, near what has been designated the Lewis and Clark State Historic Site....

, but this was later trimmed back to I-270.