There are about 169 volcanoes in the United States that scientists consider active. Most of these are located in Alaska, where eruptions occur virtually every year. Others are located throughout the west and in Hawaii (see our Volcano Activity Map for their locations).

Over 75% of the United States' active and dormant volcanoes are located in Alaska. This is due to the state's position along the "Aleutian Arc," part of the Pacific Ring of Fire where the Pacific Plate is subducting under the North American Plate. Alaska is home to more than 130 volcanoes and volcanic fields that have been active within the last 10,000 years, with about 50 of them having erupted in recorded history. While many people associate US volcanism primarily with Hawaii or the Cascade Range in Washington and Oregon, the sheer scale of the Aleutian Islands chain gives Alaska the undisputed lead in volcanic activity. These volcanoes are significant not only for geological study but also for aviation safety; ash clouds from Alaskan eruptions can frequently disrupt the busy trans-Pacific flight corridors. The Alaska Volcano Observatory (AVO) monitors these peaks 24/7 to provide early warnings for both local residents and international air traffic.