Crews worked more than a month clearing 20-feet deep snow and avalanches from Highway 410 on the east side of Mount Rainier National Park.
Spokeswoman Summer Derrey says Friday's opening is a week ahead of the goal of opening the highway by Memorial Day weekend.
The 5,400-foot pass was closed for the winter on Nov. 12. The section of Highway 410 is a scenic byway that connects with Highway 123 near Cayuse Pass for visitors to Mount Rainier.
Chinook Pass is used by an average of 4,000 vehicles a day.
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