The United States have 59 national parks which are protected area that have been established by an act of the United States Congress.
The first national park in the US was the Yellowstone, established in the late nineteen century. Yellowstone National Park is located in the states of Wyoming, Montana and Idaho and covers about 9 square kilometers. It is known for its many different ecosystems and diverse wildlife but it's above all famous for its geothermal, vulcanic and geyser activity. Abundant in the Yellowstone is also the subalpine forest.
The Grand Canyon is the most spectacular example of the power of erosion. The Canyon is cut into a low rounded mountain; it’s 277 miles long, up to 18 miles wide and has has an average depth of about one mile. The Colorado river flows through the valley. It hosts a diverse fauna, with about 70 different species of mammals, 25 species of birds and 25 species of reptiles.
The Yosemite National Park (in California) comprises a vast track of picturesque wild lands. The park highest peak reaches almost 4.000 meters above sea level. The Yosemite offers different attracting features: a great alpine wilderness, unique groves of giant sequoias and the Yosemite Valley, one of the world’s best-known examples of glacier-covered canyons.