Yellowstone National Park is a national park of the United States located mainly in the northwest corner of the state of Wyoming, with small portions extending into Montana and Idaho. The park is known for its wildlife and its many geothermal features, especially the Old Faithful geyser, one of its most popular. While it represents many types of biomes, subalpine forest is the most abundant. It is part of the South Central Rockies forests ecoregion.