Yellowstone became the first national park in the U.S. on March 1, 1872, and it helped usher in the broader national park movement. The park stretches into Wyoming, Montana, and Idaho.
(Image credit: Iris Samuels/AP)

Yellowstone became the first national park in the U.S. on March 1, 1872, and it helped usher in the broader national park movement. The park stretches into Wyoming, Montana, and Idaho.
(Image credit: Iris Samuels/AP)