In 1872, the U.S. Congress established the first national park in the United States with the creation of Yellowstone National Park.
Richert, Lucas Paul. "Yellowstone National Park founded". The Literary Encyclopedia. First published 01 February 2009; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=5972, accessed 21 April 2015.]