The Yellowstone data was among the total effects nationwide of spending by more than 327 million visitors in communities within 60 miles of a national park.
The U.S. Geological Survey has updated its threat assessments of the 161 active volcanoes in the United States, ranking 18 of them as a "very high threat" because of what's been happening inside them and their proximity to people. Yellowstone National Park's volcano ranks as a "high th…