Interstate 72

Interstate 72 (I-72) is an Interstate Highway in the midwestern United States. Its western terminus is in Hannibal, Missouri, at an intersection with U.S. Route 61 (US 61); its eastern terminus is at Country Fair Drive in Champaign, Illinois. The route runs through the major cities of Decatur, Illinois, and Springfield, Illinois. In 2006, the Illinois General Assembly dedicated all of I-72 as Purple Heart Memorial Highway. The stretch between Springfield and Decatur is also called Penny Severns Memorial Expressway, and the section between mile 35 and the Mississippi River is known as the Free Frank McWorter Historic Highway.

Route description

 * MO
 * 2.04 mi
 * IL
 * 177.25 mi
 * Total
 * 179.29 mi
 * }
 * Total
 * 179.29 mi
 * }

Missouri
I-72 runs for just over 2 mi in the state of Missouri. Its western terminus is an interchange with US 61 to the Mark Twain Memorial Bridge over the Mississippi River. This bridge connects the city of Hannibal with Illinois. Presently, there are only two exits for I-72 in Missouri.

Illinois
I-72 parallels the old Wabash Railroad from Hannibal, east through Illinois to Champaign, Illinois. The Norfolk Southern Railway operates this railroad route today.

In Illinois, I-72 runs for 182 mi. The portion of I-72 and I-172 from Springfield to Quincy is commonly referred to as the Central Illinois Expressway (CIE). , I-72 has one business route; I-72 Business (I-72 Bus.) in Jacksonville.

Near Valley City at mile-marker 42 are the Valley City Eagle Bridges. These two individual two-lane spans bridge the Illinois River in rural west-central Illinois. Near milemarker 78, a sign marks 90 degrees longitude.

At its eastern terminus in Champaign, I-72 continues as Church Street (westbound) and University Avenue (eastbound), which stay as one-way streets for an additional 3 mi into downtown Champaign.

History
First constructed in 1971, I-72 ran from Springfield at I-55 to Champaign at I-57 until the 1990's. On June 9, 1991, the American Association of State Highway and Transportation Officials (AASHTO) approved the establishment of I-172 from the western terminus of I-72 at Springfield to Fall Creek, 4 mi east of Hannibal, Missouri, though it was contingent on Federal Highway Administration (FHWA) approval. The FHWA preferred to designate the route I-72.

After discussions regarding extending an Interstate Highway through the state of Missouri, on April 22, 1995, AASHTO approved another renumbering. I-172 was renumbered in its entirety as I-72. The US 36 extension west of Fall Creek was also given the I-72 designation. The Illinois Route 336 (IL 336) expressway was renumbered to I-172 from Fall Creek to Fowler. Prior to September 2000, Mark Twain Avenue (old US 36) was composed of the current Mark Twain Avenue (now Route 79) and the portion of I-72 and US 36 west of exit 157 to the Hannibal city limits. Route 79 terminated at the foot of the old Mark Twain Memorial Bridge at the corner of Third Street and Mark Twain Avenue. Signs along the four-lane expressway portion of Mark Twain Avenue marked the route as "Future I-72", while signs along what is now Route 79 had I-72 trailblazers to direct drivers to the temporary terminus at Fall Creek, Illinois. When the new Mark Twain Memorial Bridge was completed in September 2000, I-72 was routed over the new bridge, along with US 36. Route 79 was extended along Mark Twain Avenue to terminate at exit 157.

Chicago–Kansas City Expressway
The concept of I-72 across Missouri was to create the Chicago–Kansas City Expressway, a rural four-lane highway across northern Missouri and west central Illinois from Cameron, Missouri, at I-35 to Springfield, Illinois, at I-55. This would provide a series of rural four-lane highways (I-35, US 36, I-72, and I-55) connecting Chicago to the North American Free Trade Agreement (NAFTA) Corridor (High Priority Corridor 23). This would reduce the amount of through traffic, primarily truck traffic, in the St. Louis, Des Moines, and Quad Cities metropolitan areas by serving as an alternate route for I-70 and I-80. The Missouri portion of this route is designated as part of High Priority Corridor 61.

Based on the 157 mi marker at Route 79, if/when US 36 is upgraded to Interstate standards across Missouri, the future western terminus of I-72 would be at Cameron at the intersection with I-35. Currently, the west end of I-72 route is west of US 61 and flows concurrent with US 36 into Illinois. In 2004, US 36 was upgraded to a four-lane expressway between US 61 and US 24 at the Rocket Junction (7 mi). There are three exits along this expressway: Veterans Road, Shinn Lane (Hannibal Regional Hospital), and US 24 east at the Rocket Junction. Also, an interchange with Route 15 was installed in Shelbina.

Due to funding priorities, upgrading US 36 between Macon and Hannibal was a low-priority project and was shelved. The Missouri Department of Transportation (MoDOT) committed to constructing the four-lane highway as an at-grade expressway only if the five counties served by US 36 east of Macon would contribute half of the $100 million (equivalent to $ in ) cost. Road construction to complete the 52.4 mi between Hannibal and Macon began in 2007. In August 2010, the four-lane expressway was completed from Macon to Hannibal, completing Missouri's portion of the Chicago–Kansas City Expressway.

Future
Plans exist to extend I-72 westward from its current terminus in Hannibal to St. Joseph, Missouri along the existing US 36, but the proposal was shelved for years despite most of the route being a part of the Chicago–Kansas City Expressway. In May 2023, Missouri lawmakers approved a $2.5 million study on the conversion of US 36 into I-72. The extension of I-72 is seen as a way to relieve the pressure off of I-70 as well as reduce truck traffic in St. Louis. However, in July 2023, the bill was vetoed by Governor Mike Parson who said that it was not the right time to run the study. The extension to I-29 is listed under High Priority Corridor 61B, although part of it was for the CKC and not I-72.

Auxiliary routes
I-72 currently has one auxiliary route, I-172, that serves as a freeway spur for Quincy.

Business route
Interstate 72 Business (I-72) is a business loop of I-72 in Jacksonville. It runs from the I-72/US 36/US 67 interchange southwest of Jacksonville north along the US 67 bypass of Jacksonville to the former alignment of US 36 (Morton Avenue). On Morton Avenue, I-72 Bus. runs east through downtown Jacksonville until it reaches I-72 at exit 68. This is a distance of 9.5 mi.