When you try to look at the volcanoes of the United States with these lenses, a list can begin to form. The US Geological Survey publishes a "Threat Assessment" for US volcanoes, the last one in 2018. Using their rankings, Hawaii's K?lauea is considered the most hazardous thanks to a mix of people living near the volcano and how frequently it erupts. Mount St. Helens comes in second because it is the only Cascade volcano to have erupted over the past 100 years.