Snoqualmie Pass

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Snoqualmie Pass is a mountain pass that lets Interstate 90 go through the Cascade Mountains in Washington state. It sits at about 3,015 feet in elevation and lies on the border between King and Kittitas counties. It’s the lowest of Washington’s three main year-round east–west routes, along with Stevens Pass and White Pass. I-90 carries about 29,000 vehicles each day and is the state’s only divided highway crossing from west to east.

The pass is named after the Snoqualmie people, and there’s also a small community at the summit called Snoqualmie Pass. The area gets very different weather as you gain altitude: the lower foothills have a mild climate, while the higher mountains see heavy winter snow and lots of rain most of the year. The region gets more than 100 inches of rain and over 400 inches of snow annually, with measurable precipitation on more than 170 days a year. Frost can occur any time of year, and snow can fall outside midsummer. The summit is in hardiness zone 7b, with a yearly average minimum around 9°F (-13°C). Because conditions change quickly, drivers may see warnings and sometimes need tire chains, especially for trucks. There are chain-up areas along the highway to help.

To improve safety, the old snow shed was replaced by avalanche bridges in 2014. Washington’s Department of Transportation also runs weather cameras along I-90 so travelers can check conditions before they drive.

The surrounding area has mountain chalets and about 150 people live there year-round. Winter sports are popular, and the Summit at Snoqualmie ski area is made up of four parts: Alpental, Summit West, Summit Central, and Summit East. It’s the closest ski area to Seattle. Snowmobiling is popular just east of the pass, and in good weather you might see paragliders or hang gliders above the valley near Lake Keechelus.

Long before roads, Native Americans knew this land. In the 19th century, traders and explorers used the route, looking for a good railroad path. A toll road appeared in the late 1800s, and a railroad line was built through Snoqualmie Pass in 1909, later shortened by the Snoqualmie Tunnel in 1914. The road over the pass became part of U.S. Route 10 in the 1920s and was paved by 1934. In 1969, construction began on the modern I-90 crossing. Since 1991, the Mountains to Sound Greenway Trust has worked to protect the scenic value of the I-90 corridor through Snoqualmie Pass.