 While US 6 was also one of the original 1926 U.S. Highways , the road originally served the portion of the United States east of the Rocky Mountains . The highway was not extended to the Pacific coast until 1937 , mostly following the Midland Trail . Around the time the U.S. Highway system was formed , the portion of the Midland Trail through Glenwood Canyon , known as the Taylor State Road , was destroyed by a flood . When US 6 was extended , the Works Progress Administration was rebuilding the road through the canyon and the Public Works Administration was nearing completion of a new highway over Vail Pass . In western Colorado , US 6 was routed concurrent with US 50 from the Utah state line to Grand Junction and eventually replaced US 24 from Grand Junction to near Vail . To keep these routes over the Rockies competitive with alternatives in other states , the Colorado Department of Highways relied on ingenuity to keep the roads safe . The department pioneered new machines to clear snow and various bridge and culvert designs to protect the roads from flooding . 
