Information Sheet

Mountain Passes

THREE STATE highways are closed for the winter season due to increased avalanche danger at high elevations: SR 123 over Cayuse Pass, SR 410 over Chinook Pass, and the North Cascades Highway (SR 20).

West of Chinook and Cayuse Passes, SR 410 is closed just south of Crystal Mountain Boulevard at the Mount Rainier National Park boundary. SR 123 is closed at the park boundary itself. East of Chinook Pass, SR 410 is closed at Morse Creek west of Naches. Both the Chinook and Cayuse Pass closures are encompassed within these closure points.

Thirty-six miles of State Route 20 (North Cascades Highway) are closed between seven miles east of Diablo Dam (west side of the pass) and 14 miles west of Mazama (east side of the pass). These closure points encompass Rainy Pass and Washington Pass.

Snoqualmie Pass on I-90 and Stevens Pass on US 2 -- I-90 and US 2 are the state's primary east-west highways. During the holidays traffic volumes can increase by up to 53 percent on I-90 alone. Motorists should expect the heaviest traffic volumes to occur on Tuesday, December 24, Thursday, December 26 and Sunday, December 29. Motorists traveling on those days are advised to expect delays, which can be due to poor visibility, traffic incidents, rockslides, avalanche control, and simply heavy traffic volumes.

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