In the high mountains of northwest Wyoming, among forested slopes, grassy meadows, lakes and streams, lies a country of geysers, hot springs and boiling mud pots. Across the meadows, and on the hillsides, steam can be see rising high into the air, especially in the morning. Occasionally a geyser will erupt, usually in the distance, always trailing a cloud of steam drifting in the breeze. Elk and buffalo graze along the roadside and a wilderland has been preserved in its natural state.
In the mid 1800s, Yellowstone emerged from being a secret wonderland, deep in the mountains, to become a world-famous national park and popular tourist destination. For the first time, on March 1, 1872, the United States congress declared Yellowstone to be a national park. In 1915, the park was opened to travel by automobile, and in 2003, the park was visited by 2,995,640 people.
Being remains of an ancient volcano whose cone collapsed, Yellowstone is heated by geothermal heat. Molten rock, or magma, from deep in the earth can reach close to the surface through the ancient volcanic shaft. Water, melting off from heavy winter snows, seeps into the ground to be heated to boiling temperatures by the volcanic heat. 10,000 hot springs and geysers, are preserved within the park, which are the majority of the planet's total.
Yellowstone covers 2,219,791 acres mostly in Wyoming, but also including a strip of Montana and Idaho. Park entrances can be found on the east, south, west, north and northeast. Teton National Park lies a short distance to the south, and the entrance fee includes access to both parks.
In 1870, a group of explorers known as the Washburn Expedition explored the Yellowstone area. The journal of Nathaniel Langford, a member of the party, was later published as The Discovery of Yellowstone Park. The names of many of the features in the park originated on this expedition.
For More Information:
See the National Park Service's official Yellowstone National Park site, or Wikipedia's Yellowstone National Park article.