Mount St. Helens is 34 miles west of Mount Adams, in the western part of the Cascade Range. These “sister and brother” volcanic mountains are approximately 50 miles from Mount Rainier, the highest of Cascade volcanoes. Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles southeast of Mount St. Helens.
Mount St. Helens is geologically young compared with the other major Cascade volcanoes. It formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago.