The United States has had national parks for longer than we’ve had the National Park Service. Though Yellowstone National Park was established in 1872, it was not until Aug. 25, 1916 that President Woodrow Wilson signed the bill that created the National Park Service in the U.S. Department of the Interior. The National Park Service now employs more than 20,000 people to care for and maintain the 84 million acres in the National Park System. In 2013, more than 273 million people visited a national park for recreation.