Interstate 90 at Snoqualmie Pass reopened westbound shortly before 11 a.m. Friday, after eastbound lanes reopened earlier.
Traffic was heavy westbound after the closure and a collision was adding about 90 minutes to travel time, the Washington State Department of Transportation said at noon.
The pass had been closed since about 9 p.m. Wednesday because of avalanche danger.
White Pass on Highway 12 reopened Friday afternoon after crews cleared more of the snow, ice and debris left on the roadway from snow slides.
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Highway 12 was closed late Wednesday morning. Westbound traffic was stopped near Oak Creek and eastbound traffic was stopped near Highway 123.