The volcanic activity has caused widespread disruptions to air travel across the United States, with nationwide ground stops and reroute cancellations affecting numerous airports, including major hubs like EWR (Newark), JFK (New York), and SFO (San Francisco). These measures are in place to ensure the safety of air traffic in light of potential volcanic ash clouds, which can pose significant risks to aircraft engines and visibility. Travelers are advised to check with their airlines for updates on flight schedules and potential delays.