America’s Longest Highway Goes Through Wyoming
The longest road in the United States was once the second longest: U.S. 20 from Boston, Massachusetts to Newport, Oregon, passing through Wyoming along the way.
U.S. Route 20 or U.S. Highway 20 (US 20) stretches east to west from the Pacific Northwest all the way to New England. It spans 3,365 miles and is the longest road in the United States
Then it's on to Lusk, where US 18 turns north and US 20 continues east into Nebraska.
The longest straight road in the United States, in case you were wondering, is Highway 412 beginning in Oklahoma from Hardesty to just east of Slapout for 65.5 miles. You can look at Google Earth and see that the road is perfectly straight all that way.