Yellowstone National Park is located mainly, that is to say approximately 96%, in the U.S. state of Wyoming, with the remaining 4% edging into the states of Montana and Idaho. Created in 1872 it is held to be the world’s first national park. It has been designated an International Biosphere Reserve and a UN World Heritage Site.

The park spans an area of 3,468.4 square miles (8,983 km²), comprising lakes, canyons, rivers and mountain ranges. It sits on the Yellowstone Plateau at an average elevation of 8,000 feet (3,400 m) above sea level. The plateau is bounded on nearly all sides by mountain ranges. The highest point in the park is Eagle Peak (11,358 feet or 3,462 metres) and the lowest is along Reese Creek (5,282 feet or 1,610 metres). The most prominent summit on the plateau is Mount Washburn at 10,243 feet (3,122 m). Rivers and lakes cover 5% of the land area, with the largest body of water being Yellowstone Lake, the largest high altitude lake in North America. Water erosion by rivers has cut three deep canyons into the plateau: Lewis Canyon, the Grand Canyon of Yellowstone and the Black Canyon of Yellowstone.

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The park is the result of ancient volcanic action. It is situated over the Yellowstone caldera, a supervolcano which has erupted with immense force several times over the last two million years. The area is rich in geothermal features including two thirds of the world’s geysers of which 465 are considered active in any one year. The park has one of the world’s largest petrified forests caused when ancient trees were buried by volcanic ash and debris and were transformed into stone by the leaching of minerals into their fabric. Native Americans of the Clovis culture who have lived in the area for 11,000 years used the volcanic obsidian to make arrowheads and cutting tools.

Forests comprise about 80% of the land area of the park and nearly 15% is grassland. Over 1,700 species of trees and other vascular plants are native to the area creating an ideal habitat for the resident wildlife. There are nearly 60 species of mammals in the park including the gray wolf, reintroduced after it was wiped out to protect the elk population. It now lives alongside the grizzly bear, brown bear, bison, moose, mountain lion, mule deer, white-tailed deer, mountain goat, pronghorn, big horn sheep and the threatened lynx.

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