Interstate 470 in Kansas provides a bypass loop of I-70 and the Polk-Quincy Viaduct through Downtown Topeka. The western half, Dr. Martin Luther King, Jr. Memorial Highway, constitutes a commuter route and part of U.S. 75, a major north-south route across Topeka. The eastern half runs along the tolled Kansas Turnpike between Interchanges 177 and 183.
The Interstate 70 realignment completed in 2001 at the East Topeka Interchange slightly extended I-470 east to a point beyond the site of the former Topeka Service Area.
The section of Interstate 470 that overlays the Kansas Turnpike was constructed in 1955 and 1956, with the entire turnpike opening on October 21, 1956. The portions of the Kansas Turnpike that carry I-35, I-70, and I-470 were approved as part of the Interstate Highway System by the Federal Highway Administration (FHWA) in 1957. The remainder of I-470 west of the toll road was constructed in the 1960s.1
Interstate 470 was part of the proposed urban Interstate numerology in Kansas approved by the American Association of State Highway Officials (AASHO) on November 10, 1958. 470 was selected for the circumferential highway around Topeka instead of 270 to avoid the duplication of route numbers, since U.S. 270 was already established in the state. Interstate Route 70S was a previous suggestion by the Kansas State Highway Commission submitted to AASHO on June 4, 1958:
In the case of Topeka, we chose to recommend that Route No. 70 pass through the heart of downtown Topeka, as in the case of the City of Wichita. It is our belief that the major route number should be carried on that part of the urban network that carries the major traffic volumes and should pass through or near the center of the metropolitan area. With this in mind, we suggest that the by-pass around the west, south and east parts of Topeka, be designated as No. 70S.