Interstate 49 in Missouri

Northern terminus of I-49 at the Grandview Triangle in Kansas City, Missouri

I-49 enters Missouri from the Arkansas state line on the Bella Vista Bypass near Pineville. After continuing north for five miles (8.0 km), US 71 rejoins I-49 at exit 4 and is concurrent with it for the remainder of its length. It passes through many smaller communities before reaching Joplin. In Joplin, I-49 junctions with I-44 and begins a short overlap with I-44 between exits 11 and 18, heading east.

Just a few miles east of Joplin, I-49 leaves I-44, heads north, and enters Carthage. I-49 then passes through Nevada and other communities before reaching the Kansas City area. I-49 intersects with I-470 and I-435, which provide connections to I-70, Downtown Loop, I-35, and I-29.

In south Kansas City, at Bannister Road just north of the Grandview Triangle, the I-49 designation ends, the freeway continues as US 71, which proceeds into downtown Kansas City as Bruce R. Watkins Memorial Drive.

Former southern terminus of I-49 as seen in 2011, near Pineville, Missouri; a connection from this point to CR 34 west of Bella Vista, Arkansas, opened in 2021.

Arkansas and Missouri pursued an I-49 designation for US 71 and I-540 for a number of years. In the early 2000s, there were plans by both states to renumber the roadway as such between I-44 west of Joplin and I-40 at Fort Smith once new roadway had been completed around Bella Vista, Arkansas, and north to Pineville, Missouri.[2] However, the American Association of State Highway and Transportation Officials (AASHTO) Special Committee on U.S. Route Numbering denied the I-49 designation at their annual meeting in September 2007 because none of the new roadway was under construction.[3]

The I-49 upgrade involved removing all at-grade intersections and constructing interchanges and overpasses at 15 sites between Harrisonville and Lamar.[4] The two-year project represented a shift in funding priorities for the Missouri Department of Transportation (MoDOT), which, in 2007, had announced the indefinite postponement of its portion of the Bella Vista bypass project, citing a $139-million (equivalent to $178 million in 2021[5]) funding gap in Arkansas between construction costs and toll revenues, and Arkansas's commitment to only a two-lane bypass constructed over six years.[6] MoDOT announced the Joplin-to-Kansas City upgrade of US 71 in August 2010, to be done with the intention of bringing the I-49 designation to Missouri.[7]

MoDOT began installing I-49 trailblazer signage (without shields) as well as gantry signs and milemarkers, about 1200 signs in all, in February 2012. Signage bearing I-49 shields were covered or turned from view until the I-49 designation was given final approval by the Federal Highway Administration (FHWA). This includes milemarkers at 0.2-mile (0.32 km) intervals along the entire alignment apart from I-44.[8]

The I-49 designation in Missouri became official at noon on December 12, 2012.[9] The designation applies to 180 miles (290 km) of current US 71 between Bannister Road (Route W) in south Kansas City and Route H at Pineville (McDonald County) which was upgraded to Interstate standards beginning in 2010.[7] The last of the upgrade projects were completed in December 2012, but some designations about seven miles (11 km) north of the Arkansas state line still have not been built to meet Interstate standards.

In 2012, Missouri had $40 million (equivalent to $47.3 million in 2021[5]) available for its portion of the Bella Vista bypass but moved the money elsewhere in 2013.[10] They planned on using money from a proposed constitutional amendment which would have raised the sales tax; however, this was defeated by voters in August 2014. Arkansas announced it will not extend its section to Missouri until construction begins on the Missouri section.[11]

In March 2019, the Missouri Highways and Transportation Commission approved the remaining funding needed to complete the portion of the Bella Vista Bypass within the state.[12] On April 1, 2020, the Missouri Highways and Transportation Commission awarded a $58.7 million contract for the construction of the five-mile (8.0 km) portion of highway. Construction started on May 11, 2020,[13] and the entire bypass opened on October 1, 2021, following a ribbon-cutting ceremony held the day prior.[14] With this, I-49 is fully complete within the state.