2021-03-01 Yellowstone first National Park (1872) Yellowstone first National Park (1872) March 1, 2021 Yellowstone first National Park (1872) established by the Forty-Second U.S. Congress and signed into law by President Ulysses S. Grant on March 1, 1872 the first national park in the world 1,221,773 acres U.S. National Park