Answer: Yellowstone

The first U.S. national park was, fittingly, the scenic Yellowstone Caldera and surrounding land. Although it is now one of the most trafficked national parks in the United States, at the time the land was set aside as a national park, very few had even laid eyes on it.

In fact, we can thank the tireless efforts of one man for the preservation of the region: Ferdinand V. Hayden. Hayden had explored part of the general region in the late spring of 1860 and was stunned by how diverse and beautiful the area was. He returned in 1871 with an enormous team that included surveyors, photographers, and painters to document Yellowstone.

Armed with evidence of its grand and diverse landscape, he returned to Washington, D.C. and showed the evidence to Congress and President Ulysses S. Grant. In 1872, President Grant signed the bill that secured Yellowstone’s position as a national park.