Yellowstone was the first national park established by Congress. President Ulysses S. Grant signed the bill into law on March 1, 1872. The park was created after the Washburn-Langford-Doane Expedition of 1870. (Nathaniel P. Langford eventually became Yellowstone's first superintendent.) Expedition members were impressed by the geysers, canyon and Yellowstone Lake.
Yellowstone had been visited earlier in the century by John Colter, who talked glowingly of the place. Colter had been a part of the Lewis and Clark expedition and later worked for a fur trader near Yellowstone. People thought Colter made up all the things about the area and called the place "Colter's Hell"