All of the known historical eruptions have occurred in Washington , Oregon and in Northern California . The two most recent were Lassen Peak in 1914 to 1921 and a major eruption of Mount St. Helens in 1980 . Minor eruptions of Mount St. Helens have also occurred , most recently in 2006 . In contrast , volcanoes in southern British Columbia , central and southern Oregon are currently dormant . The regions lacking new eruptions keep in touch to positions of fracture zones that offset the Gorda Ridge , Explorer Ridge and the Juan de Fuca Ridge . The volcanoes with historical eruptions include : Mount Rainier , Glacier Peak , Mount Baker , Mount Hood , Lassen Peak , and Mount Shasta
major eruption of Mount St. Helens in 1980
1980 eruption of Mount St. Helens
Cascade Volcanoes