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.

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 roughly parallel to US 97 for about 3 miles (4.8 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. The route throughout most of Oregon serves as an important link between Central and Southern Oregon and far Northern California to Boise, Idaho.

Under the initial 1925 plan for the United States Numbered Highway System, US 20 was originally planned to follow the Columbia River from Astoria to Pendleton and continue southeast into Idaho. The Oregon Highway Commission requested that US 30 be assigned to the Columbia River Highway instead and have US 20 truncated at Pocatello, Idaho. The American Association of State Highway Officials ultimately agreed to truncate US 20 further to Yellowstone National Park, but later extended it via central Oregon in 1940.

A 10-mile (16 km) section of the Corvallis–Newport Highway between Chitwood to Eddyville was replaced by the Oregon Department of Transportation (ODOT) in the early 21st century to accommodate higher traffic volumes. The section, originally opened in 1917, was winding and had no shoulder for vehicle breakdowns. Construction on a straighter, 5.5-mile (8.9 km) route began in 2005 and was planned to be completed in 2009, but landslides and other hazards caused delays. In 2012, ODOT took over the project from the original design–build contractor after an agreement was reached in their liability dispute. The project was completed in October 2016 at a cost of $365 million.

In 2017, the Oregon legislature designated Oregon’s 451-mile stretch of U.S. Route 20 as the state’s official Medal of Honor Highway. Twelve roadside signs were placed along the route to honor Oregon’s Medal of Honor recipients. Oregon was the first state to designate a border-to-border route as its official Medal of Honor Highway. Supporters hope other states will extend the Medal of Honor designation from the Oregon border to highway’s eastern terminus in Massachusetts.

The Oregon section of US 20 consists of the following highways numbered using ODOT's internal numbering system (see Oregon highways and routes), from west to east:

• The Corvallis-Newport Highway No. 33;
• Part of the Corvallis-Lebanon Highway No. 210;
• The Albany-Corvallis Highway No. 31;
• The Santiam Highway No. 16;
• Part of the McKenzie Highway No. 15;
• The McKenzie-Bend Highway No. 17;
• The Central Oregon Highway No. 7.

Milepoints are as reported by ODOT and do not necessarily reflect current mileage. Z indicates overlapping mileage due to construction longer than established route, and – indicates negative mileage behind established beginning point. Segments that are locally maintained may be omitted. For routes traversing multiple named state highways, each milepoint is preceded by the corresponding state highway number. 

County	Location	Milepoint	Destinations	Notes
Lincoln	Newport	33 0.00	US 101 south – Waldport, Florence US 101 north – Depoe Bay, Lincoln City	Western terminus of US 20
	​	33 5.62	US 20 Bus. east – Toledo
	​	33 5.74	OR 229 – Siletz, Toledo
	​	33 7.49	US 20 Bus. west – Toledo
	​	33 10.34	Pioneer Mountain summit, elevation 377 feet (115 m)
	​	33 23.18	OR 180 east (Eddyville–Blodgett Road) – Nashville, Summit
	​	33 31.08	Cline Hill summit, elevation 770 feet (230 m)
Benton	​	33 38.28	Dudley Hill summit, elevation 860 feet (260 m)
	​	33 39.39	OR 180 west (Eddyville–Blodgett Highway) – Summit, Nashville
	​	33 41.78	Gellately Hill summit, elevation 789 feet (240 m)
	​	33 44.57	OR 223 north – Wren, Kings Valley
	​	33 49.73	OR 34 west – Alsea, Waldport	Western end of concurrency with OR 34
	Corvallis	33 55.67 91 (2)84.07	OR 34 east to I-5	Interchange; eastern end of concurrency with OR 34; eastbound exit and westbound entrance
			OR 99W south – Junction City, Eugene	Interchange; western end of concurrency with OR 99W; westbound exit and eastbound entrance
		91 (2)83.42 210 –0.05	OR 99W north (NW 3rd Street) – Monmouth, McMinnville	Eastern end of concurrency with OR 99W
		210 0.00 31 0.10	To OR 34 east / I-5 – Lebanon
Benton–Linn county line	Albany	31 10.44	Willamette River
Linn		31 11.28 58 2.25	OR 99E south (Pacific Boulevard SW) – Junction City	Western end of concurrency with OR 99E
		58 (2)1.45 16 –0.03	OR 99E north to I-5 north – Salem, Portland	Eastern end of concurrency with OR 99E; eastbound exit and westbound entrance
		16 1.04– 16 1.08	I-5 – Eugene, Roseburg, Salem, Portland	Exit 233 on I-5
	​	16 6.55	OR 226 east – Crabtree, Scio, Lyons
	Lebanon	16 12.80	OR 34 west – Corvallis
	Sweet Home	16 27.07	OR 228 west (Holley Road) – Brownsville, Halsey
		16 31.19	Viewpoint (Foster Lake)
	​	16 46.93	Historical marker (Santiam Wagon Road)
	​	16 63.64	Tombstone Pass summit, elevation 4,236 feet (1,291 m)
	​	16 71.52	OR 126 west (McKenzie Highway) – Springfield, Eugene	Western end of Route 126 concurrency
	​	16 74.90	OR 22 west – Detroit, Salem
Linn–Jefferson county line	​	16 80.77	Santiam Pass summit, elevation 4,817 feet (1,468 m)
Jefferson	​	16 84.57	Viewpoint (Mount Washington)
Deschutes	​	16 99.53	Historical marker (Santiam Pass Road)
	Sisters	16 100.12 15 Z92.03	OR 242 west – McKenzie Pass
		15 93.07 17 0.00	OR 126 east – Redmond, Prineville	Eastern end of concurrency with OR 126
	​	17 9.09– 17 9.18	Viewpoint
	Bend	17 18.51	US 97 Bus. north (NE 3rd Street)	Interchange; western end of concurrency with US 97 Bus.
		17 19.86	US 97 south – Mt. Bachelor, Klamath Falls	Interchange; eastbound exit only
			US 97 north – Redmond, Portland	Interchange; westbound exit only
		17 20.99 7 0.51	US 97 Bus. south (NE 3rd Street) – Klamath Falls	Eastern end of concurrency with US 97 Bus.
	​	7 19.95	Historical marker (prehistoric river)
	​	7 20.56	Horse Ridge summit, elevation 4,291 feet (1,308 m)
	​	7 35.65	OR 27 north – Prineville Reservoir
Lake	No major junctions
Harney	​	7 103.03	Historical marker (Bannock War)
	​	7 104.69	US 395 south – Wagontire, Valley Falls, Lakeview	Western end of concurrency with US 395
	Burns	7 131.50	OR 78 east (East Monroe Street) – Crane, Winnemucca
	​	7 134.29	US 395 north – John Day, Pendleton	Eastern end of concurrency with US 395
	​	7 144.25	Historical marker (Fort Harney)
	​	7 155.09	Historical marker (Great Basin)
	​	7 160.79	Stinkingwater Pass, elevation 4,848 feet (1,478 m)
	​	7 177.54	Drinkwater Pass, elevation 4,212 feet (1,284 m)
Malheur	​	7 232.99	Vines Hill summit, elevation 2,886 feet (880 m)
	​	7 238.78	Graham Boulevard (Vale–West Highway No. 451) – Bully Creek Reservoir
	Vale	7 245.46	Graham Boulevard (Vale–West Highway No. 451)
		7 246.39	US 26 west (Glenn Street North) – Unity, John Day	Western end of concurrency with US 26
	​	7 253.48	Viewpoint (Trenkel Hill vista)
	Cairo Junction	7 258.20	OR 201 north to I-84 – Ontario	Western end of concurrency with OR 201
	Nyssa	7 265.97	OR 201 south – Adrian, Lake Owyhee	Eastern end of Route 201 concurrency
		7 266.82	US 20 east / US 26 east – Nampa, Boise	Continuation into Idaho across Snake River
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

US 20 has 2 business routes in Oregon: one in Toledo, and one in Bend.

• Oregon portal
• U.S. Roads portal
• Ghosts of Highway 20

• Media related to U.S. Route 20 in Oregon at Wikimedia Commons
• U.S. 20: Route crosses the Cascades and heads east - The Oregonian

U.S. Route 20
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