State Route 20 (North Cascades Highway) Now Closed For Season Due to Avalanche Hazard Incoming snowfall followed by anticipated warm and wet weather has prompted the Washington State Department of Transportation to close State Route 20, also known as the North Cascades Highway, for the season as of Wednesday, Nov. 10.ย Closure points will be milepost 134/Ross Dam Trailhead on the west side and milepost 171/Silver Star Gate on the east. Related: Attention Backcountry Skiers: […] Industry News SnowBrains | November 17, 2021 0 Comments