Lassen Volcanic National Park in northeastern California preserves one of the United States’ most varied volcanic landscapes, centered on Lassen Peak, the world’s largest plug dome volcano and the southernmost non-extinct volcano in the Cascade Range. The area, long known to the Atsugewi and later used as a landmark by emigrants, gained federal protection before eruptions from 1914 to 1917 helped bring about the park’s creation in 1916. Its unusual significance lies in containing all four major volcano types together, along with prominent hydrothermal features, heavy snowfall, and terrain shaped by both volcanism and past glaciation. Ongoing monitoring and conservation reflect its still-active nature.