Yellowstone National Park (U.S. National Park Service)

The World’s First National Park. On March 1, 1872, Yellowstone became the first national park for all to enjoy the unique hydrothermal and geologic features. Within Yellowstone’s 2.2 million acres, visitors have unparalleled opportunities to observe wildlife in an intact ecosystem, explore geothermal areas that contain about half the world’s …

https://www.nps.gov/yell/index.htm