Snoqualmie Pass Becomes a Highway


It took decades before the value of Snoqualmie Pass was recognized. The Department of Transportation improved it several times, turning it into a major thoroughfare.

The route that would ultimately become Interstate 90 through Snoqualmie Pass through the Cascade Mountains of Washington State started out as a popular Indian trail. As white settlers emigrated to the Seattle area in the 1850s, it became obvious that a route through the mountains was needed. Early efforts resulted in a toll road that was completed in 1884.

When the Northern Pacific Railroad completed their line to Puget Sound in 1887, the railroad crossed the Cascades at Stampede Pass, southeast of Snoqualmie Pass, and ended at Tacoma. The railroad drew much of the traffic away from Snoqualmie Pass. Though it was still used, the road was not maintained and it fell into disrepair. Travel became difficult.

In 1898, gold was discovered in the Alaskan Klondike region. Seattle became the supply depot for miners heading north. The gold rush also spurred new interest in gold digs in the Cascades. This generated new interest in a road over Snoqualmie Pass. Two thousand dollars was appropriated from the state to repair the road. It was soon back in use.

The first motorized car went over the road in 1905. Bert Harrison drove a 1898 Fryer-Miller automobile from Indianapolis to Seattle. He had the most trouble at Lake Keechelus where they kept high-centering on rocks and stumps. The Alaska-Yukon-Pacific Exposition in 1909 included a transcontinental car race that would end at Seattle. King, Kittitas, Yakima, and Walla Walla counties came up with money to improve the Snoqualmie Pass road. Records show that 109 cars went over the pass that year. The event generated enough interest that the governor committed to spreading gravel on the road and other minor maintenance.

The road remained in static condition until 1915, when the world exposition was held in San Francisco. Promoters made further improvements to Snoqualmie Pass and the major north-south highway between California and Puget Sound, in an effort to encourage travelers going to and from the Expo to tour the Pacific Northwest. In July of that year, the Washington State Department of Transportation officially dedicated the route as the Snoqualmie Pass Highway and declared it the state’s first passable road between eastern and western Washington. Over the next decade, inns and auto camps sprang up along the route.

In 1926, the state highway department finally began to plan for paving the road. They would remove blind curves, pave, and build new bridges. Portions of the road were relocated. In the late 1920s, oil was added to the road to help keep dust down. In 1927, speed limits ranged from 30 to 40 miles an hour, though it was difficult to ever achieve that. State patrol officers used stop watches to measure speed traveled by motorists.

For the first time the road was open all winter long during 1931-32. Between 1934 and 1936, 47 new bridges were built. In 1934, Governor Clarence Martin dedicated a 17-mile stretch of paved road at Snoqualmie Pass. A pontoon bridge was built across Lake Washington from Mercer Island in 1939, which shortened the route considerably.

The road was maintained throughout World War II was an important supply route. In 1952, work began to expand the route to four lanes. The highway department also began adding concrete snow sheds. Further improvements were made throughout the 60s and 70s to straighten out curves, add shoulders, etc., that would accommodate vehicles that traveled at faster speeds. Today, constant avalanche danger has crews looking for more ways to improve this very important stretch of Interstate 90 through Washington State.


  1. “Snoqualmie Pass: From Indian Trail to Interstate,” Yvonne Prater, The Mountaineers, Seattle, WA, 1995.