Interstate 90 is a critical transportation corridor connecting the large population and business centers of the Puget Sound with the agricultural industries and recreational activities of eastern Washington.
The I-90 traveler may experience congestion, delays due to avalanche closures, rough pavement conditions, rock slide activity and potential wildlife collisions on the highway. The uninterrupted movement of people, freight and business over Snoqualmie Pass is essential to our quality of life and the economic vitality of Washington state. WSDOT is expanding a 15-mile stretch of I-90 from Hyak to Easton to meet both the current and future needs of this transportation corridor.
When this project is complete, travelers will experience a safer, more efficient six-lane freeway, minimized closures as a result of avalanches and rock slides, and a smoother ride due to new pavement designed to last 50 years. Wildlife habitat on either side of I-90 will be reconnected with the installation of new bridges and culverts, protecting both wildlife and the traveling public.
Long before the early explorers came to the Northwest, Native Americans on both sides of the mountains carved foot trails across the Central Cascades, including Snoqualmie Pass, to hunt deer, elk and other game animals, fish for salmon and gather berries. They also traveled to this area to gather wild plants for food, medicinal purposes and basket weaving. Pacific Northwest tribes like the Snoqualmie Indian Tribe and Yakama Nation used foot and horse trails across the Central Cascade mountains for trading as it had the lowest pass elevation in the territory.
How did people originally travel across Snoqualmie Pass?
In 1854, the United States Government began scouting the Cascades for railroad routes and wagon trails. In 1865, construction started on a wagon road on the west side of the pass to lure settlers to Seattle. But on the east side, just a trail existed and settlers often used rafts and barges to cross Lake Keechelus. Finally by 1867, the wagon road stretched from Seattle to Ellensburg. In 1884, a toll was placed on the road to help pay for its maintenance. By 1905, harsh winters and flooding forced settlers to rebuild the road several times to provide a safer and passable road.
What route did people travel over Snoqualmie Pass?
In 1905, the first automobile drove over Snoqualmie Pass, but the road was far from adequate. That same year, the Washington State Department of Highways was created and plans to improve the road over the pass soon began. In partnership with King and Kittitas Counties, the road was upgraded to promote the 1909 Alaska–Yukon–Pacific Exposition in Seattle, which promoted an auto race across the pass. In 1915, a new two-lane road was built called Sunset Highway, which created a permanent transportation route that connected eastern and western Washington. Later in 1926, this highway was rebuilt on the abandoned Milwaukee Railroad right-of-way.
How did the route over Snoqualmie Pass develop?
It wasn't until 1931 that the Department of Highways successfully kept the road open through an entire winter. In 1934, the highway was renamed Public State Highway No. 2, and an ambitious campaign to pave a 17-mile stretch of roadway at the summit began. A few years later, the road was renamed US Route 10. A rest area, Travelers’ Rest, was built in 1938, and the Lake Keechelus and Airplane Curve Snowsheds were built in 1950.
When was I-90 created?
In the 1950s and 1960s, US Route 10 was widened to four lanes. Also during this time, state highways were renumbered to meet the American Interstate Highway System, creating Interstate 90. In the 1970s, major highway projects near the pass were completed that replaced concrete pavement, straightened roadway curves and made other safety improvements. The efforts in the 1970s kept traffic moving across Snoqualmie Pass for the next 30 years.
What improvements have been accomplished so far?
Phase 1 - Hyak to Keechelus Dam
Phase 1 covers the first five miles of the 15-mile corridor from Hyak to Keechelus Dam. The 2005 gas tax provided $551 million to widen I-90, build and replace bridges including two new avalanche bridges, stabilize rock slopes and expand chain-up and chain-off areas. Construction started in 2009. The first three miles was completed in 2013 and the remaining two miles were completed in 2018.
Phase 2 - Keechelus Dam to Stampede Pass interchange
Phase 2 covers the next two miles of the corridor from Keechelus Dam to the Stampede Pass interchange. Project savings from Phase 1 provided $108 million to widen I-90, build and replace bridges, stabilize rock slopes and build the first wildlife overcrossing in the project corridor. Construction started in 2015 and was completed in 2019.
In 2015, the Legislature secured $426 million with the Connecting Washington funding package to complete the remaining eight miles of the corridor from the Stampede Pass interchange to Easton. The remaining eight miles of the project are divided into three phases and widens I-90 from four to six lanes, straightens curves, adds and replaces bridges and culverts, addresses wildlife connectivity and expands chain-up areas.
Since 2006, the South Central Region Communications team has provided project information to the community at various fairs, festivals and events. Visit our online open house to learn more about construction this summer.
Final Environmental Impact Statement Documents
The Federal Highway Administration and WSDOT prepared a 2005 Draft Environmental Impact Statement (EIS) and a 2008 Final EIS for proposed improvements to a 15-mile portion of I-90 east of Snoqualmie Pass in the Cascade Mountains from Hyak to Easton. Consistent with National Environmental Policy Act (NEPA) regulations, the US Forest Service and US Bureau of Reclamation were cooperating agencies in preparing these documents. Following the 2008 Record of Decision (ROD) by FHWA and concurrence from the cooperating agencies, WSDOT proceeded with implementation of the selected alternative and construction of the I-90 project has continued since 2009.