Editing Interstate 72 (section)

==History==
[[Image:I-72 North of Seymour Illinois.jpg|thumb|left|A section of I-72, north of [[Seymour, Illinois]], looking west]]
First constructed in 1971, I-72 ran from [[Springfield, Illinois|Springfield]] at [[Interstate 55 in Illinois|I-55]] to [[Champaign, Illinois|Champaign]] at [[Interstate 57 in Illinois|I-57]] until the 1990s. On June 9, 1991, the [[American Association of State Highway and Transportation Officials]] (AASHTO) approved the establishment of [[Interstate 172|I-172]] from the western terminus of I-72 at Springfield to [[Fall Creek, Illinois|Fall Creek]], {{convert|4|mi|km|spell=in}} east of [[Hannibal, Missouri]], though it was contingent on [[Federal Highway Administration]] (FHWA) approval. The FHWA preferred to designate the route I-72.<ref name=aashto_1991>{{cite web |url=http://cms.transportation.org/sites/route/docs/1991-USRN_Cmte.PDF |title=Report of the Special Committee on U.S. Route Numbering to the Executive Committee |author=American Association of State Highway and Transportation Officials |date=June 9, 1991 |access-date=December 19, 2007 |archive-url=https://web.archive.org/web/20061013050357/http://cms.transportation.org/sites/route/docs/1991-USRN_Cmte.PDF |archive-date=October 13, 2006 |url-status=dead }}</ref><ref name=I-Guide172>{{cite web|url=http://www.interstate-guide.com/i-172_il.html|publisher=Interstate-Guide.com|title=Interstate 172 Illinois}}{{self-published source|date=January 2024}}</ref>

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 [[U.S. Route 36 in Illinois|US&nbsp;36]] extension west of Fall Creek was also given the I-72 designation. The [[Illinois Route 336]] (IL&nbsp;336) expressway was renumbered to I-172 from Fall Creek to [[Fowler, Illinois|Fowler]].<ref name=I-Guide172/><ref name=aashto_1995>{{cite web |url=http://cms.transportation.org/sites/route/docs/1995-USRN_Cmte.pdf |title=Report of the Special Committee on U.S. Route Numbering to the Standing Committee on Highways |date=April 23, 1995 |access-date=December 19, 2007 |author=American Association of State Highway and Transportation Officials |archive-url=https://web.archive.org/web/20070204073850/http://cms.transportation.org/sites/route/docs/1995-USRN_Cmte.pdf |archive-date=February 4, 2007 |url-status=dead }}</ref>
[[File:Interstate 72 bridge over the Illinois River.jpg|thumb|The bridge of Interstate 72 and U.S. Route 36 over the [[Illinois River]], near [[Valley City, Illinois|Valley City]], [[Illinois]].]]
Prior to September 2000, Mark Twain Avenue (old US&nbsp;36) was composed of the current Mark Twain Avenue (now [[Missouri Route 79|Route&nbsp;79]]) and the portion of I-72 and US&nbsp;36 west of exit&nbsp;157 to the Hannibal city limits. Route&nbsp;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&nbsp;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&nbsp;36. Route&nbsp;79 was extended along Mark Twain Avenue to terminate at exit&nbsp;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 [[Interstate 35 in Missouri|I-35]] to [[Springfield, Illinois]], at [[Interstate 55 in Missouri|I-55]]. This would provide a series of rural four-lane highways (I-35, US&nbsp;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 [[Greater St. Louis|St. Louis]], [[Des Moines metropolitan area|Des Moines]], and [[Quad Cities]] metropolitan areas by serving as an alternate route for [[Interstate 70 in Missouri|I-70]] and [[Interstate 80 in Iowa|I-80]]. The Missouri portion of this route is designated as part of [[High Priority Corridor]] 61.

Based on the {{convert|157|mi|km|adj=on}} marker at Route&nbsp;79, if/when [[U.S. Route 36 (Missouri)|US&nbsp;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 [[U.S. Route 61 in Missouri|US&nbsp;61]] and flows concurrent with US&nbsp;36 into Illinois. In 2004, US&nbsp;36 was upgraded to a four-lane expressway between US&nbsp;61 and [[U.S. Route 24 in Missouri|US&nbsp;24]] at the Rocket Junction ({{Convert|7|mi|km|spell=in}}). There are three exits along this expressway: Veterans Road, Shinn Lane (Hannibal Regional Hospital), and US&nbsp;24 east at the Rocket Junction. Also, an interchange with [[Missouri Route 15|Route&nbsp;15]] was installed in [[Shelbina, Missouri|Shelbina]].

Due to funding priorities, upgrading US&nbsp;36 between [[Macon, Missouri|Macon]] and [[Hannibal, Missouri|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&nbsp;36 east of Macon would contribute half of the $100 million (equivalent to ${{Formatprice|{{inflation|US-GDP|100000000|2010}}}} in {{Inflation/year|index=US-GDP}}{{Inflation/fn|index=US-GDP}}) cost. Road construction to complete the {{convert|52.4|mi|km}} 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.<ref name=three>{{cite press release |author= North Central District |year=2007 |title=U.S. 36 4-Laning Project: Contract Awarded for Route 36 Four-lane Project from Shelbina to Macon |publisher=Missouri Department of Transportation}}{{full|date=June 2023}}</ref>