Yellowstone National Park

On March 1, 1872, President Ulysses S. Grant signed the Yellowstone National Park Protection Act, establishing the first national park in the United States. Spanning 3,468 square miles across northwestern Wyoming with small portions in Montana and Idaho, the park sits atop a volcanic hotspot. Ferdinand Hayden's 1871 geological survey, accompanied by photographer William Henry Jackson and painter Thomas Moran, provided Congress with visual documentation that helped secure the legislation. The park contains over 10,000 geothermal features, including more than 300 geysers.