US 2 follows the route of several
wagon roads and early state highways that themselves followed the route of the
Skykomish River and the
Great Northern Railway, a
transcontinental railroad that was completed in 1893. A wagon road from
Snohomish to
Skykomish was completed in the late 1880s, while another wagon road along the
Wenatchee River from
Leavenworth to
Sunnyslope was completed by 1904. The modern-day route of US 2 between Snohomish and Monroe was completed as a county wagon road in 1904. The
state of Washington began maintaining
State Road 7 in 1909, traveling from
Peshastin to
Spokane on what would become the
Sunset Highway and US 2. The easternmost segment of US 2 within Washington, from Spokane to
Newport, was added to the state highway system in 1915 as
State Road 23 and renamed to the
Pend Oreille Highway two years later. State Road 7 was renumbered to
State Road 2, part of an east–west highway connecting
Seattle to
Spokane. The Stevens Pass Highway was opened on July 11, 1925, and traveled from Everett along the Skykomish River and over
Stevens Pass towards
Leavenworth. The Tumwater Canyon section northwest of Leavenworth opened to traffic on September 1, 1929, and later straightened in 1937. The highway was transferred to state maintenance from the
Department of Highways in 1931 as
State Road 15. The
United States Highway System was adopted by the
American Association of State Highway Officials (AASHO) on November 11, 1926, and included a shorter US 2, traveling from
Bonners Ferry, Idaho to the
Upper Peninsula of Michigan, and several routes along the modern route of US 2 in Washington. The corridor of US 2 was signed as
US 10 from Peshastin to Spokane and
US 195 from Spokane to Newport, co-signed with State Road 2 and State Road 6, respectively. The
Washington primary and secondary state highway system was adopted by the
Washington State Legislature on March 17, 1937, and the three highways that comprise the present route of US 2 were included in the system as
Primary State Highway 15 (PSH 15) from Everett to Peshastin,
PSH 2 from Peshastin to Spokane, and
PSH 6 from Spokane to the
Idaho state line in Newport via a short branch route. US 10 was relocated to a southern route in 1939, crossing the
Columbia River at
Vantage, and the former route was replaced by
US 10 Alternate the following year. A proposal from representatives of the highway departments of Idaho and Washington to extend US 2 to Everett was considered by the AASHO's U.S. Route Numbering Committee in January 1946, but was vetoed. The proposal resurfaced during the committee's meeting on December 20, 1946, and was approved as a replacement of US 10 Alternate from Everett to Bonners Ferry and US 195 from Spokane to Newport. The
Washington state highway system was changed to its current "sign route system" beginning in January 1963 with a
state highway renumbering. Under the new system, Interstate highways, U.S. routes, and state routes replaced the primary and secondary highways and were codified under the
Revised Code of Washington in 1970. The existing wooden trestle was used by eastbound traffic until it was replaced by a new bridge in 2002. US 2 was routed north of Wenatchee onto the
Olds Station Bridge, renamed in 1991 to honor
Richard Odabashian, over the Columbia River in 1975, while the former alignment was designated as
SR 285 in 1977. The present
two-lane expressway north and east of Snohomish was approved in 1969 and opened in October 1983; it was originally intended to also include an unfinished bypass of
Monroe. US 97 had its concurrency with US 2 extended from Sunnyslope to Orondo along the east side of the Columbia River in 1987 after US 97 was moved onto the former route of
SR 151. The Stevens Pass Greenway, which became a
National Forest Scenic Byway on April 14, 1992, was re-designated as a
National Scenic Byway on September 22, 2005. Within Newport, US 2 had an unsigned spur route that traveled on the southbound lanes of
ID-41 on the Idaho state line until 1997, when
SR 41 was created to avoid confusion. The intersection between US 2 and US 97 east of Peshastin was replaced by a new
diamond interchange completed in October 2008 as part of general improvements to the two highways' concurrency from Peshastin to Sunnyslope. The current interchange between US 2 and the
North Spokane Corridor, a spur route of
US 395, was opened in November 2011 to coincide with the opening of the northernmost of the future freeway.
Everett–Skykomish corridor In the early 2000s,
WSDOT began planning a series of 56 projects to improve the US 2 corridor between Snohomish and Skykomish, where the highway is two lanes wide and has been the site of over 2,600 collisions between 1999 and 2007 that caused 47 fatalities. A study, conducted by WSDOT in 2007, divided the corridor into four segments, each with a specialized development plan. The study suggested the expansion of the limited-access highway from Snohomish to the western city limits of Monroe to four lanes, including an interchange at Bickford Avenue that was later completed in September 2013. A wider median with
rumble strips was added to some sections of US 2 between Snohomish and Monroe in 2019. WSDOT plans to move US 2 onto a northern bypass of Monroe, which would avoid the business district and intersect
SR 522 with a roundabout. From Monroe to
Gold Bar, US 2 would be expanded to a four-lane highway, with a roundabout connecting the highway to the city of Gold Bar, and become a two-lane highway with wider shoulder lanes to Skykomish. Seasonal traffic congestion in the Sultan area, which causes backups that overflow onto side streets, have inspired proposals to build an additional bypass, a two-street
couplet, or a freeway along the Stevens Pass corridor. In 2023, the Sultan city government endorsed plans to widen US 2 to four lanes and replace several intersections with roundabouts. In addition to the freeway expansion, WSDOT is considering a total replacement of the westbound Hewitt Avenue Trestle that would cost between $750 million to $1 billion. One of the options in the early feasibility study conducted in 2017 included a vehicle toll, which sparked public outcry on social media. The study also lists an increased
gas tax, federal grants, and
public-private partnerships as potential revenue sources for the project. ==Major intersections==