The United States National Park System was created by President Woodrow Wilson on August 25, 1916, 44 years after the establishment of Yellowstone in 1872 by President Ulysses S. Grant.
There are 401 areas comprising the national park system, covering more than 84 million acres in every state, the District of Columbia, American Samoa, Guam, Puerto Rico, and the Virgin Islands.
The largest national park in the United States is Wrangell-St. Elias National Park and Preserve in Alaska at 13.2 million acres.
Four national park sites have a waterway named Green River running through them: in the west, the Green River flows through Dinosaur National Monument, Glen Canyon National Recreation Area, and the Canyonlands National Park. In the east, a different Green River passes through Mammoth Cave National Park.
The deepest national park is not the Grand Canyon, but Kings Canyon in California with a depth of 8,200 feet.