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Johnston Ridge Visitor Center: 100 miles N of Portland, 178 miles S of Seattle

Named in 1792 by Capt. George Vancouver for his friend Baron St. Helens, Mount St. Helens was once considered the most perfect of the Cascade peaks, a snow-covered cone rising above lush forests. However, on May 18, 1980, all that changed when Mount St. Helens erupted with a violent explosion that was previously unknown in modern times. The eruption blew out the side of the volcano and removed the top 1,300 feet of the peak, causing the largest landslide in recorded history. This blast is estimated to have traveled at up to 650 mph, with air temperatures of up to 800°F (425°C). The eruption also sent more than 540 million tons of ash nearly 16 miles into the atmosphere. This massive volume of ash rained down on an area of 22,000 square miles and could be measured as far away as Denver.

The volcano and 110,000 acres of both devastated and undisturbed forests have been preserved as Mount St. Helens National Volcanic Monument. Several visitor centers provide information on the eruption and the subsequent changes that have taken place here. At press time, the volcano was again active, with a new cone forming inside the crater. This renewed activity, though not as dramatic as the 1980 eruption, makes Mount St. Helens the only active volcano in the contiguous United States.