I-670 was extended east over the south leg of the Alphabet Loop when Interstate 35 was relocated to run along the north and west legs of the Downtown belt route. Missouri applied to the American Association of State Highway officials (AASHTO) for these route changes on November 15, 1975. Action on I-670 was deferred at that time while the I-35 relocation was approved on November 12, 1976.
Interstate 670 in Kansas City was fully opened to traffic in January 1990 as the final route of the original Kansas Interstate Highway System to be completed. The viaduct that carries the Kansas section of I-670 cost $75 million of the overall $130 million price tag to build I-670.2,3 Completion of the elevated roadway garnered the grand award by the Consulting Engineers Council of Missouri in March 1991.4
Approved by voters in 1973, the Kansas City Convention Center was located wholly north of Interstate 670 between Broadway and Wyandotte Street in southwest Downtown when it opened in 1976. A major expansion project for the complex broke ground on October 24, 1991 to more than double the size of the Bartle Hall exhibit space.5 Supported by four 260 foot pylons, the new Bartle Hall was constructed above Interstate 670 between Broadway and Central Street. The $144.4 million facility was formally opened by the city during a ribbon cutting ceremony held on September 24, 1994.6 A second lid over Interstate 670 would be added later.
Kicking off with a ceremonial groundbreaking on June 17, 2005, further expansion of the Kansas City Convention Center complex added the Grand Ballroom over I-670 between Central and Wyandotte Streets. The initial budget of $145.1 million included $7.6 million in state funds to both demolish the closed westbound on-ramp from Wyandotte Street and remove the Central Avenue overpass above I-670.7 The ballroom opened on April 28, 2007.
Another project underway by 2005, four blocks to the east of the Grand Ballroom, involved construction of a new concert and indoor sports arena. The project resulted in the permanent closure of the McGee Street westbound off-ramp on January 4, 2006.8 $26 million in road work along I-670, from summer to October 2007, included the addition of a new westbound off-ramp to replace the McGee Street exit further east at Locust Street and Truman Road.8