Cascade Loop Scenic Byway, International Selkirk Loop
North Cascades Scenic Byway, Sherman Pass Scenic Byway, Whidbey Scenic Isle Way
Major junctions
West end
US 101 in Discovery Bay
Major intersections
I-5 in Burlington
SR 9 in Sedro-Woolley
US 97 near Okanogan
SR 21 in Republic
US 395 in Colville
SR 31 in Tiger
East end
US 2 in Newport
Location
Country
United States
State
Washington
Counties
Jefferson, Island, Skagit, Whatcom, Chelan, Okanogan, Ferry, Stevens, Pend Oreille
Highway system
State highways in Washington
Interstate
US
State
Scenic
Pre-1964
1964 renumbering
Former
← SR 19
→ SR 21
State Route 20 (SR 20), also known as the North Cascades Highway, is a state highway that traverses the U.S. state of Washington. It is the state's longest highway, traveling 436 miles (702 km) across the northern areas of Washington, from U.S. Route 101 (US 101) at Discovery Bay on the Olympic Peninsula to US 2 near the Idaho state border in Newport. The highway travels across Whidbey Island, North Cascades National Park, the Okanagan Highland, the Kettle River Range, and the Selkirk Mountains. SR 20 connects several major north–south state highways, including Interstate 5 (I-5) in Burlington, US 97 through the Okanogan–Omak area, SR 21 in Republic, and US 395 from Kettle Falls to Colville.
SR 20's path across the Cascades follows one of the oldest state roads in Washington, established in 1896 as a wagon route. The wagon road fell into disuse within a decade, and the state government postponed the construction of a new route across the North Cascades for several decades. The development of the Skagit River Hydroelectric Project spurred boosters to lobby the state for a new route across Washington Pass, which was opened in 1972.[3] SR 20 originally ran from the Mount Vernon area to Okanogan. By 1973, SR 20 was extended over existing state highways in northern Washington, replacing SR 113 and portions of SR 525 and SR 536 near Port Townsend; SR 30 and SR 294 from Tonasket to Tiger; and part of SR 31 from Tiger to Newport.
Although US 12 has a larger east–west extent, SR 20 is the longest highway in Washington at 436.13 miles (701.88 km), only 5.3 miles (8.5 km) longer than US 12.[1] The highway has been called "The Most Beautiful Mountain Highway in the State of Washington."[4]
North Cascades Highway
^ abMultimodal Planning Division (January 27, 2017). State Highway Log Planning Report 2016, SR 2 to SR 971 (PDF) (Report). Washington State Department of Transportation. pp. 417–478. Retrieved November 16, 2017.
^"47.17.080: State route No. 20". Revised Code of Washington. Washington State Legislature. 1970. Retrieved November 16, 2017.
^"SR 20 - North Cascades Highway - History". Washington State Department of Transportation. Retrieved November 16, 2017.
^Gulick, Bill (1996). A Traveler's History of Washington. Caxton Press. p. 333. ISBN 0-87004-371-4.
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Global Information
US 101 in Discovery Bay
US 2 in Newport
