There are 170 active or potentially active volcanoes in the United States. USGS Volcanoes monitors volcanic activity across the country and delivers forecasts, warnings and information about volcano hazards. Volcanoes come in many shapes and sizes: 🌋 Tall and pointy (Composite volcano, Mount Rainier National Park) 🌋 Short and round (Cinder cone, Lassen Volcanic National Park) 🌋 High and wide (Shield, Hawai'i Volcanoes National Park) 🌋 Expansive and flat (Caldera, Yellowstone National Park) B