Lassen Volcanic National Park is a United States National Park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome Volcano in the World and the southern-most volcano in the Cascade Range. Lassen Volcanic National Park started as two separate national monuments designated by President Theodore Roosevelt in 1907: Cinder Cone National Monument and Lassen Peak National Monument.
The source of heat for volcanism in the Lassen area is subduction off the Northern California coast of the Gorda Plate diving below the North American Plate. The area surrounding Lassen Peak is still active with boiling mud pots, stinking fumaroles, and churning Hot Springs. Lassen Volcanic National Park is one of the few areas in the world where all four types of volcano can be found (plug dome, shield, cinder cone, and strato).
The park is accessible via State Routes SR 89 and SR 44. SR 89 passes north-south through the park, beginning at SR 36 to the south and ending at SR 44 to the north. SR 89 passes immediately adjacent the base of Lassen Peak.
There are a total of five vehicle entrances to the park: the north and south entrances on SR 89, and unpaved roads entering at Drakesbad and Juniper Lake in the south, and Butte Lake in the northeast. The Park can also be accessed by trails leading in from Caribou Wilderness to the east, as well as the Pacific Crest Trail, and two smaller trails leading in from Willow Lake and Little Willow Lake to the south.
A large lodge (the Lassen Chalet) with concession facilities formerly was located near the south-west entrance, but was demolished in 2005. A new, full-service visitor center was constructed in the same location, and opened to the public in 2008. Near the old lodge location was also located Lassen Ski Area, which ceased operation in 1992; all infrastructure has been removed.