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.
Pennsylvania
The Pennsylvania Department of Transportation, abbreviated as PennDOT, owns of the of roadway in the state, making it the fifth-largest state highway system in the United States. The Pennsylvania Turnpike system is long, with the mainline portion stretching from Ohio to Philadelphia and New Jersey. It is overseen by the Pennsylvania Turnpike Commission. Another major east–west route is Interstate 80, which runs primarily in the northern tier of the state from Ohio to New Jersey at the Delaware Water Gap. Interstate 90 travels the relatively short distance between Ohio and New York through Erie County, in the extreme northwestern part of the state.
Primary north–south highways are Interstate 79 from its terminus in Erie through Pittsburgh to West Virginia, Interstate 81 from New York through Scranton, Lackawanna County and Harrisburg to Maryland and Interstate 476, which begins north of the Delaware border, in Chester, Delaware County and travels to Clarks Summit, Lackawanna County, where it joins I-81. All but of I-476 is the Northeast Extension of the Pennsylvania Turnpike, while the highway south of the main line of the Pennsylvania Turnpike is officially called the "Veterans Memorial Highway", but is commonly referred to by locals as the "Blue Route".