Interstate 470 in Missouri connects southern Kansas City with Independence, providing a bypass of the Kansas City metropolitan area to the southeast and a commuter route to Lee’s Summit. The freeway overlaps with U.S. 50 from the Three Trails Crossing Memorial Highway interchange with I-49 and I-435 to Exits 7A/B, and doubles as Missouri Route 291 on its north-south section between Exit 10 and Exit 16. Old U.S. 50 is designated Route 350 between Interstate 470 and I-435 through Raytown and Kansas City.
The state of Missouri submitted Interstate 170, a connector between I-435 and I-70 southeast of Kansas City, as part of the Urban Route Numbering proposals to AASHO on July 31, 1958. The route was changed to Interstate 470 since it constituted a loop and approved by AASHO on November 10, 1958.1
The alignment of Intestate 470 appeared on the Missouri Official Highway Map by 1964 from the Grandview Triangle Interchange with U.S. 71 and I-435 east to then-U.S. 71 Bypass north of Lee’s Summit. U.S. 71 Bypass ran north from U.S. 50 to U.S. 40 as part of the planned route. Missouri Route 291 replaced U.S. 71 Bypass by 1975, with a short stretch of expressway completed by 1969 from south of U.S. 40 to 39th Street. The 1983-84 Missouri Official Highway Map shows the Interstate fully opened to traffic.
The Grandview Triangle Interchange, where I-435, I-470 and U.S. 71 came together in south Kansas City, was redesigned during an eight year project completed in May 2008. The original junction was chronically congested, having been designed when the area was vastly more rural. Suburban growth both along I-435 and U.S. 71 overran the exchange with commuter traffic, leading to the need for the $300 million upgrade. Construction removed some of the left-hand ramps and expanded the freeway mainlines among other improvements. The junction was renamed the Three Trails Crossing Memorial Highway to reflect the end of the Grandview Triangle Interchange era.
A $46-million project between 2006 and June 2010 improved the junction of Interstate 470 with U.S. 50 leading east and Route 350 in Lee’s Summit. A new split-diamond interchange with Pryor Road and Blue Parkway frames the cloverleaf interchange with the U.S. 50 freeway leading south through Lee’s Summit. The new ramps provide local access to the Summit Woods and Summit Fair retail area, reducing traffic on U.S. 50 to the adjacent Chipman Road exit.2
A new diamond interchange opened to traffic along I-470 at Strother Road on August 19, 2010. The $15-million project extended Strother Road and provides additional access to industrial park areas served by Lee’s Summit Municipal Airport (LXT).3
The 1981 Rand McNally North American Road Atlas showed Interstate 470 open from the Grandview Triangle east to Route 350 at Lee’s Summit.
U.S. 50 was relocated onto I-470 and I-435, bypassing Kansas City, when the east-west section of I-470 opened. U.S. 50 previously followed Blue Parkway northwest to Swope Parkway, where it combined with U.S. 56 west to Interstate 35 at Merriam, Kansas.