There are 169 young volcanoes in the United States, many of which are considered hazardous due to their proximity to populated areas. The USGS considers many of the more dangerous volcanoes to be under-monitored, lacking adequate scientific instruments on the ground to measure activity and potential threats. Many volcanoes lack any instruments, and the seismometers at other sites are inadequate for useful analysis. One of the most active volcanoes in Washington, Glacier Peak, only has a single seismometer. Improved monitoring capabilities can provide more timely warnings for evacuations and emergency response coordination, and mitigate the impacts of the travel disruptions. Early warnings are particularly critical for air traffic control, which needs to be made aware of ash-producing eruptions in time to reroute airplanes.