Washington State Route 20

Washington State Route 20
State	WA
Type	SR
Route	20
Maint	Washington State Department of Transportation
Length mi	436.67
Established	1964
Direction a	West
Terminus a	Anacortes
Direction b	East
Terminus b	Idaho state line
Counties	Skagit, Whatcom, Chelan, Okanogan, Douglas, Ferry, Stevens

Washington State Route 20 is a major east–west highway in the state of Washington. Stretching from Anacortes on Fidalgo Island to the Idaho state line at Pine Creek Pass, the route crosses diverse terrain including coastal islands, river valleys, the Cascade Range, and high desert plateau. It connects regional centers such as Mount Vernon, Sedro-Woolley, Winthrop, Okanogan, and Spokane and serves as the state's longest highway.

Route description

State Route 20 begins on Fidalgo Island at a ferry-linked hub near Port of Anacortes and proceeds through urban corridors of Anacortes and industrial districts adjacent to the Puget Sound Naval Shipyard and Whidbey Island ferry routes. The highway crosses the Skagit River near Mount Vernon and follows the Skagit Valley into Sedro-Woolley, intersecting with arterial roads that serve Burlington and Interstate 5. Climbing toward the Cascade Range via the North Cascades Highway, the roadway traverses recreational areas including Ross Lake National Recreation Area, North Cascades National Park, and the Lake Chelan National Recreation Area, passing near Diablo Lake and the Skagit River hydroelectric facilities. Descending into central Washington, SR 20 serves agricultural communities in the Methow River Valley by Twisp and Winthrop before crossing the Okanogan River toward Okanogan and Pateros. East of the Cascades the route proceeds near Wenatchee and East Wenatchee corridors, parallels the Columbia River briefly, and continues past Omak toward Malo and Republic environs, then eastward through Kettle Falls and Colville corridors before reaching the Idaho state line adjacent to Bonners Ferry access.

History

The corridor that became SR 20 evolved from early territorial roads and wagon routes used during the Oregon Trail era and from Great Northern Railway influences in northeastern Washington. Portions of the present route follow alignments of former state highways, including predecessors designated in 1937 under the Washington highway renumbering and subsequent adjustments in the mid-20th century tied to the Federal Aid Highway Act of 1956. The formal SR 20 designation emerged in the 1964 Washington codification, consolidating segments such as former Primary State Highways and secondary connectors between Anacortes, Sedro-Woolley, and eastward communities. Construction of the North Cascades Highway segment during the 1970s completed a continuous crossing of the Cascade Range, enabled by civil engineering projects through steep canyons and alpine passes near Washington Pass and Rainy Pass. Over time SR 20 has been affected by environmental litigation involving U.S. Forest Service land use planning, seasonal avalanche control tied to Washington State DOT operations, and community-driven preservation efforts in towns like Winthrop and Twisp. The highway has also been the focus of economic development initiatives with agencies such as the Washington State Department of Commerce and regional transit planning involving the Skagit Council of Governments and North Central Washington Regional Transportation Planning Organization.

Major intersections

SR 20 intersects numerous state and federal routes and local arterials, including connections with SR 525 and Anacortes spur in Anacortes, a junction with I‑5 near Mount Vernon, intersections with SR 9 at Sedro-Woolley, and a crossing with US 97 in central Washington near Pateros and Okanogan. The North Cascades segment meets access roads to Diablo Lake and Ross Lake, and farther east SR 20 links with SR 153 at Winthrop and with US 2 and US 395 near the Spokane Valley and Colville corridors before terminating at the Idaho state line.

Junctions and auxiliary routes

Auxiliary alignments and spurs associated with the route include the Anacortes spur serving the Port of Anacortes ferry and industrial waterfront, short connector segments near Sedro-Woolley that interface with Burlington freight routes, and local linkages providing access to North Cascades Highway trailheads and recreational facilities administered by agencies such as the National Park Service, Washington State Parks, and the U.S. Forest Service. Junctions with county roads create multimodal links to airports like Paine Field and Wenatchee Valley Regional Airport, railheads served by BNSF Railway and Union Pacific Railroad, and intermodal facilities in Spokane and Wenatchee.

Traffic and maintenance

Traffic volumes along SR 20 vary widely, with urban segments near Anacortes and Mount Vernon experiencing higher commuter and freight flows documented by the Washington State Department of Transportation. Mountain sections such as Washington Pass and Rainy Pass receive seasonal tourism traffic to North Cascades National Park, often requiring snow removal, avalanche mitigation, and temporary closures coordinated with the National Weather Service and state avalanche centers. Pavement rehabilitation, bridge inspections, and safety projects are managed by the Washington State Department of Transportation in partnership with county public works departments in Skagit, Chelan, Okanogan, and Ferry. Freight movements link to ports including the Port of Seattle and Port of Anacortes, while public transit and shuttle services by regional operators like Skagit Transit and community transit providers supplement access for recreational and rural populations.

Future developments and projects

Planned and proposed projects affecting SR 20 range from pavement and bridge upgrades prioritized by the Washington Transportation Commission to corridor safety improvements funded under state packages influenced by the Moving Washington transportation proposals and statewide transportation revenue measures. Environmental reviews and permitting for expansions near sensitive areas involve coordination with the U.S. Fish and Wildlife Service, Washington State Department of Ecology, and tribal governments including Confederated Tribes of the Colville Reservation and Samish Indian Nation. Local economic initiatives by organizations such as the Okanogan County Economic Development Council and tourism campaigns by Visit North Central Washington influence investment in wayfinding, rest area amenities, and multimodal linkages to trails managed by the Washington Trails Association. Long-term discussions include potential realignments to improve flood resiliency near the Skagit River and capacity enhancements to serve growing freight demand to ports like Port of Everett and Grays Harbor Port Authority.

Category:State highways in Washington (state)