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.
Highway 12 was closed late Wednesday morning. Westbound traffic was stopped near Oak Creek and eastbound traffic was stopped near Highway 123.