Yellowstone National Park is located primarily in Wyoming, although it also extends into Montana and Idaho. It was established by the U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone, the first National Park in the U.S. and widely held to be the first national park in the world and is known for its wildlife and its many geothermal features, especially Old Faithful Geyser. It has many types of ecosystems, but the subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.