There are 13 active business routes of Interstate 70 in Colorado. Interstate 70 (I-70) spans Colorado in an east–west fashion, holding many business loops and spurs along the way, varying from lengths of 0.22 miles (0.35 km) to 27.47 miles (44.21 km), with a total of 55.51 miles (89.33 km). Four other business routes also used to exist within the state.

U.S. Highway 6 (US 6) is a part of the United States Numbered Highway System that travels from Bishop, California, to Provincetown, Massachusetts. In the U.S. state of Colorado, US 6 is an east–west highway stretching from Utah to Nebraska. Much of the route overlaps other highways in Colorado, and, as a result, much of US 6 is unsigned.