What's the longest highway in the US?
U.S. Route 20
U.S. Highway 20 (US 20) is an east–west United States highway that stretches from the Pacific Northwest all the way to New England. The "0" in its route number indicates that US 20 is a coast-to-coast route. Spanning , it is the longest road in the United States, and particularly from Newport, Oregon to Boston, Massachusetts, the route is roughly parallel to that of the newer Interstate 90 (I-90), which is in turn the longest Interstate Highway in the U.S. There is a discontinuity in the official designation of US 20 through Yellowstone National Park, with unnumbered roads used to traverse the park.
U.S. Route 20 in Massachusetts
U.S. Route 20 is the longest numbered highway in the entire country and also holds the distinction of being the longest numbered highway in the state, edging out Route 28 by merely a mile (Route 28 is long).