U.S. Route 30 or U.S. Highway 30 (US 30) is an east–west main route of the United States Numbered Highway System, with the highway traveling across the Northern U.S. With a length of 3,072 miles (4,944 km), it is the third-longest U.S. Highway, after US 20 and US 6. The western end of the highway is at US 101 in Astoria, Oregon; the eastern end is at Virginia Avenue, Absecon Boulevard, and Adriatic Avenue in Atlantic City, New Jersey. The "0" as the last digit in the number indicates that it is a coast-to-coast route and a major east–west route. Despite long stretches of parallel and concurrent Interstate Highways, it has not been decommissioned unlike other long-haul routes such as US 66. It is also the only U.S. Highway that has always been coast-to-coast since the beginning of U.S. Numbered Highway System.

U.S. Route 20 or U.S. Highway 20 (US 20) is an east–west United States Numbered Highway that stretches from the Pacific Northwest east to New England. The "0" in its route number indicates that US 20 is a major coast-to-coast route. Spanning 3,365 miles (5,415 km), it is the longest road in the United States, and, in the east, the route is roughly parallel to Interstate 90 (I-90), which is 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.