Yellowstone National Park is famous worldwide for its vast forests, abundance of wildlife – including a wide variety of North American megafauna, and its natural landmarks like Old Faithful Geyser. The Park, which spans over 3,400 square miles, was established by Congress and signed into law by President Ulysses S. Grant in 1872, making it the first national park ever established. In addition to over 350 species of animals, over 1,000 plant species call the park home.  The first actual flora of the park was published in 1886 by a man named Frank Tweedy.  Tweedy was a topographical engineer born in New York City in 1854. Between 1884-85, Tweedy was in Yellowstone mapping the topography of the park for a project with the U.S. Geological Survey.