Yellowstone National Park is a national park of the United States located in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress through the Yellowstone National Park Protection Act and signed into law by President Ulysses S. Grant on March 1, 1872. Yellowstone was the first national park in the U.S. and is also widely held to be the first national park in the world.