U.S. Route 20 (US 20) is an east–west United States highway. The "0" in its route number indicates that US 20 is a coast-to-coast route. Spanning 3,365 miles (5,415 km), it is the longest road in the United States, and the route roughly parallels that of Interstate 90 (I-90). There is a discontinuity in the official designation of US 20 through Yellowstone National Park, with unnumbered roads used to traverse the park.

It and US 30 break the general U.S. Route numbering rules in Oregon, since US 30 actually starts north of US 20 and runs parallel to the north throughout the state. The two overlap and continue in the "correct" positioning near Caldwell, Idaho. This is because US 20 was not a planned coast-to-coast route while US 30 was. US 20 originally ended at the eastern entrance of Yellowstone Park; it was extended in 1940.

The highway's eastern terminus is in Boston, Massachusetts, at Kenmore Square, where it meets State Route 2. Its western terminus is in Newport, Oregon, at an intersection with US 101, within a mile of the Pacific Ocean.

U.S. Route 20 (US 20) is a major west–east cross-state highway in the northern part of the U.S. state of Oregon, especially east of the Cascade Mountains. It connects U.S. Route 101 in Newport on the central Oregon Coast to the Idaho state line east of Nyssa.

Route description

US 20 starts at an intersection with US 101 in Newport, and travels eastward over the Central Oregon Coast Range to Corvallis. In Corvallis, it intersects Oregon Route 99W (OR 99W) and briefly travels concurrent with OR 34 before proceeding northeast to Albany. From Albany, US 20 briefly travels concurrent with OR 99E before turning east through Lebanon and Sweet Home and entering the Cascade Mountains. It intersects OR 126 west of Santiam Pass and the two routes travel concurrent through Sisters. US 20 then continues eastward and southward to Bend, where it travels concurrent with US 97 for about 5 miles (8.0 km) before turning east through Brothers and Riley. At Riley, US 20 travels concurrent with US 395 through Hines and Burns to about 2 miles (3.2 km) northeast of Burns. From Burns, US 20 continues east through Juntura and Vale. In Vale, US 20 travels concurrent with US 26, and the two highways continue east to Cairo Junction, south of Ontario, and turn south, where they then also travel concurrently with OR 201 to Nyssa. Eastward from Nyssa, US 20/US 26 continue to the Idaho state line.

U.S. Highway 20 in Nebraska is a major east–west artery running across northern Nebraska. It enters the state in sparsely populated northwest Nebraska as a rural two lane highway. It exits concurrently with Interstate 129 and U.S. Highway 75 by a Missouri River crossing at South Sioux City.

Route description

U.S. 20 enters Nebraska from Wyoming near the Niobrara River and continues 9 miles (14 km) before encountering the first city on the route, Harrison. It then crosses the White River near Fort Robinson and, at Crawford heads northeast where it meets with U.S. Highway 385 for two miles (3 km) before entering Chadron. It then heads southeast toward Hay Springs where it again turns in an east/northeasterly direction toward Merriman. At this point U.S. 20 is only about 5 miles (8.0 km) from the South Dakota border. From Merriman it heads east through the small towns of Cody, Nenzel, and Kilgore to Valentine. This 196-mile (315 km) section of U.S. 20 has been noted by the Department of Roads for its history and natural beauty and has been designated as the "Bridges to Buttes Byway."