 I @-@ 70 enters Colorado from Utah , concurrent with US 6 and US 50 , on a plateau between the north rim of Ruby Canyon of the Colorado River and the south rim of the Book Cliffs . The plateau ends just past the state line and the highway descends into the Grand Valley , formed by the Colorado River and its tributaries . The Grand Valley is home to several towns and small cities that form the Grand Junction Metropolitan Statistical Area , the largest conurbation in the area locally known as the Western Slope . The highway directly serves the communities of Fruita , Grand Junction and Palisade . Grand Junction is the largest city between Denver and Salt Lake City and serves as the economic hub of the area . The freeway passes to the north of downtown , while US 6 and 50 retain their original routes through downtown . US 6 rejoins I @-@ 70 east of Grand Junction ; US 50 departs on a course toward Pueblo . 
