Colorado 470 is a state maintained freeway connecting the southwestern quadrant of the metropolitan area. Originally planned as Interstate 470, the federal funding was reallocated to the 16th Street Mall project in downtown Denver. As a result, at that time, the Colorado 470 freeway was not likely to be constructed. However, with local funds, the freeway was eventually built. It is unlikely that this route will receive an Interstate designation because of its construction through the use of local funds. In August 2000, an extension of Colorado 470 from Interstate 70 north to U.S. 6 opened. The intent is for the extension of Colorado 470 to link to the future connector between the Northwest Parkway, which was opened in November 2003. By 2010, it is expected that the gap between the northwestern terminus of Colorado 470 and the western terminus of the Northwest Parkway (formerly referred to as "W-470") will be connected, thus forming a complete beltway around the metropolitan area.
Colorado 470 is the only Colorado state route routinely referred to with a "C-" suffix, so locals call it "C-470." Perhaps this is opposed to "I-470."
Colorado 470 Highway Guides
And here are some recommended off-site links related to Interstate 470, Colorado 470 (C-470), Extension 470 (E-470), Western 470 (W-470), and the Northwest Parkway: