Warning sign at the west portal of the original Great Northern Railway Cascade Mountain tunnel. The tunnel was built in 1900. It replaced a series of switchbacks that took trains over Stevens Pass, Washington. The west portal was located at small town named Wellington. The deadliest avalanche in American history occurred at Wellington on March 1, 1910. 96 people were killed when 2 trains were swept off the tracks by the avalanche and thrown into the Tye River canyon below Wellington. The tunnel roof collapsed in early 2008. Water, as much one million gallons, accumulates behind the collapse and discharges without warning. It is not safe to approach the west portal of the old Cascade Tunnel. Photo by Michele Harris July 18, 2009.