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.
List of U.S. Highways in Maryland
The following is a list of U.S. Highways in Maryland. There are currently 14 U.S. Highways that exist entirely or partially in the U.S. state of Maryland. Seven of these are primary U.S. Highways while seven are auxiliary U.S. Highways that may or may not be related to one of the primary U.S. Highways. The longest primary U.S. Highway in Maryland is U.S. Route 40 (commonly abbreviated US 40) at . The shortest primary U.S. Highway in Maryland is US 11 at . The longest auxiliary U.S. Highway in Maryland is US 301 at . The shortest auxiliary U.S. Highway in Maryland is US 522 at . All U.S. Highways are maintained by the Maryland State Highway Administration except for the portions that run through Baltimore, Hagerstown, and Cumberland. Maryland has five former U.S. Highways; those five are shaded in dark gray in the list.