The west side of Mount St. Helens  offers the quickest access and has some of the finest views and the most developed facilities. Nearly 900,000 visitors take this route each year. With five elaborate visitors centers and a wide paved road reaching the center of the monument, this is the place most folks view the volcano.
The main access route to the west side is Highway 504, the Spirit Lake Memorial Highway. Starting from the town of Castle Rock  (exit 49 from I-5), Highway 504 offers a 54-mile scenic climb right to the heart of the volcanic destruction that resulted from the 1980 eruption.
A secondary access is Highway 505, which cuts east from I-5 at the tiny town of Toledo (exit 60) and joins Highway 504 after 16 miles near the town of Toutle (TOOT-ul).
Following Spirit Lake Memorial Highway from I-5 to its terminus inside the national monument you’ll pass by Castle Rock , Silver Lake , Hoffstadt Bluffs , Toutle Valley , and the Forest Learning Center .