Yellowstone National Park the oldest, one of the largest, and probably the best-known national park in the United States. It is situated in northwestern Wyoming and partly in southern Montana and eastern Idaho and includes the greatest concentration of geothermal features in the world. The park was established by the U.S. Congress on March 1, 1872, as the nation's—and the world's—first national park. It was designated a World Heritage site in 1978. The park, almost all of which remains undeveloped, covers 3,468 square miles (8,983 square km) and consists mostly of broad volcanic plateaus with an average elevation of 8,000 feet (2,440 meters). Among the mountain ranges that protrude into the park are the Gallatin Range on the northwest, the Absaroka Range on the east, and the Tetons along the park's southern boundary. The park is also surrounded by the Custer, Shoshone, Teton, Targhee, Beaverhead, and Gallatin national forests.
Rocky Mountain National Park , is more than 415 square miles and has 114 named peaks over 10,000 feet. One of the more popular hiking trails is the Keyhole Route on Longs' Peak. At 14,255 feet, Longs' Peak is the highest peak in the Rocky Mountain National Park and the fifteenth tallest in Colorado. The park contains three distinct ecosystems which correspond to elevation: the montane, which is 7,000 to 9,000 feet above sea level; the subalpine ecosystem which is 9,000 to 11,500 feet and spans the tree line; and the alpine tundra, at the top which is over 11,500 feet. Birds and animals add color and interest to the landscape. The park contains 65 species of mammals, 260 species of birds, and 900 species of plants. Black bears, mountain lions, and bobcats live in the park, but seldom are seen. Moose and mule deer are more visible. In autumn, herds of American elk roam the park and frequently are visible, even at the lower elevations.