I-44 approached by US 71 (now part of I-49) just south of Joplin
I-44 enters Missouri in Newton County at the eastern terminus of the Will Rogers Turnpike, 200 yards (180 m) south of the Kansas state line. The first interchange in Missouri is the eastern terminus of both U.S. Route 166 (US 166) and US 400. This highway next goes through southern Joplin and then begins to run concurrently with I-49/US 71 at exit 11 just after entering Jasper County. The freeway turns to a more eastern heading (the old route of US 166), and then I-49/US 71 splits off to the north at exit 18.
I-44 next enters Lawrence County. Near Mount Vernon, the highway curves to the northeast. The section of highway to Halltown is a completely new highway, not supplanting any previous highways. At Halltown, the road curves back to due east, beginning to follow the general pathway of old US 66, which it does all the way to downtown St. Louis. I-44 then goes around the western and northern sides of Springfield, serving as the western terminus of the James River Freeway, as well as crossing both Route 13 and US 65. The Interstate Highway continues northeast, bypassing Lebanon.
This section needs expansion. You can help by adding to it. (June 2008)
I-44 follows the general route of, and completely replaced, historic US 66 from Halltown (exit 58, the junction with a cutoff section of US 66 since renumbered as Route 96) to downtown St. Louis. From rural Joplin at exit 15 to Mount Vernon at exit 49, it largely follows a decommissioned section of US 166.
Originally, the eastern terminus of I-44 was at the intersection with I-55, I-64, I-70, and US 40, by the Poplar Street Bridge. This was changed when the Stan Musial Veterans Memorial Bridge opened on February 9, 2014, rerouting I-70 over the river along a more northern alignment. I-44 now takes the old I-70 alignment through the below-grade section of roadway in St. Louis, extending the Interstate for about 1.5 miles (2.4 km) to its new eastern terminus at a directional interchange with I-70 near Cass Avenue;[2] the eastbound lanes of I-44 join the westbound lanes of I-70, and the westbound lanes of I-44 branch off the eastbound lanes of I-70.[2]
Signed as exits 18A (south) and 18B (north); eastern terminus of I-49/US 71 concurrency; access to George Washington Carver National Monument and Neosho National Fish Hatchery
First diverging diamond interchange in North America, existing interchange converted in 2009;[4] access to Fantastic Caverns, Ozark Empire Fairgrounds, and Dickerson Park Zoo
All of I-44's business routes are in Missouri. Most of these business loops were the former US 66. Missouri also has the unusual occurrence of a business loop and business spur from the same Interstate intersecting (the Waynesville–St. Robert loop and the Ft. Leonard Wood spur).
^ ab"Traffic Control Sheets"(PDF). Missouri Highways and Transportation Commission. June 8, 2010. Archived from the original(PDF) on May 14, 2016. Retrieved February 23, 2022.