The 1st United States National Park and also considered to be the 1st National Park in the world, Yellowstone National Park is located in Wyoming, Montana and Idaho.  Ulysses S Grant signed the park into being on March 1, 1872.  Larger than the states of Rhode Island and Delaware with 2,219,789 acres, Yellowstone National Park joins with Grand Teton National Park and the surrounding National Forests to form the Greater Yellowstone Ecosystem.  The park became a UNESCO World Heritage site in 1978.

Sitting on top of the Yellowstone Caldera which is believed to be an active supervolcano, the Park has a large number of geysers and boiling springs.  The best known geyser is Old Faithful and it was the 1st to be given a name.  The tallest geyser is Streamboat, which does not erupt on a regular basis.  

Yellowstone is home to over 17,000 species of trees and flowering plants.  The hot springs provide areas for unusual bacteria to thrive including Thermus Aquaticus which is useful in replicating DNA.  There are well over 50 different large animal species including the bison, black bears, wolves, grizzly bears, elk and moose. Park management of some populations has been controversial at times.

Visitors have come to Yellowstone for hundreds of years to fish, hunt and observe natural phenomena.  The 1st detailed exploration took place in 1869 and after a geological survey in 1871, Congress and President Grant created the park.  Since then tourism has grown. Starting with stage coaches and horses, train travel and on to automobiles, the number of visitors reached over 4 million a year in 2014.   Hiking, camping, fishing and observing the hydrological features and the wildlife are the major attractions.  Until 1970, visitors had interacted with the bears, even feeding them.  Fortunately, feeding is now prohibited, but it is much more difficult to see the bears.