Interstate 470 was the original designation for the Colorado 470 between Interstate 70 in Golden and Interstate 25 in Lone Tree near Centennial. The route, which today forms the southwestern quadrant of the Denver Beltway, was adopted in 1969 by the Denver Metropolitan Area Transportation Study. In December 1968, Interstate 470 was added to the Interstate Highway System under the Federal Highway Act in 1968.1 The route went through various studies through 1972, when the final environmental impact statement was released and submitted to the Federal Highway Administration.
As was the case with several Interstate Highways studied in the early 1970s, the environmental impact statement brought controversy. Governor Dick Lamm, who was elected on a platform that included the elimination of Interstate 470 from Denver metropolitan area transportation plans, created the Interstate 470 Ad Hoc Commission. The commission studied the route and conducted public sessions. In December 1976, the commission recommended that Interstate 470 should be withdrawn from the Interstate Highawy System and a parkway (Future Colorado 470) be constructed in its place.1 Shortly thereafter, the Colorado Department of Highways concurred with the findings of the commission. On June 23, 1977, the Federal Highway Administration approved eliminating Interstate 470.1
In the ensuing decade, Colorado 470 was built in stages, starting with the first section opening in 1980 and the last section opening in 1990. While Colorado 470 is a freeway, there are several substandard elements, especially the interchange with Colorado 75 (which has a sharp off-ramp) and an access point to an industrial site on northwestbound Colorado 470. Funds previously earmarked for Interstate 470 were earmarked not only to the Colorado 470/Centennial Parkway corridor but also to improvements on U.S. 85 (Santa Fe Drive segment) and other transportation improvements throughout the region.
Starting in the 1990s, the Denver Beltway was extended east and north as a toll road via Extension 470 ("E-470") and the Northwest Parkway in Broomfield. These sections were never considered for inclusion in Interstate 470. There are currently no plans to add any section of the Denver Beltway back to the Interstate Highway System.
