Yellowstone National Park has the distinction of being the world's first national park. With an area of 3,472 sq mi (8,992 sq km), Yellowstone is the largest national park in the lower 48 states. This is an area larger than Rhode Island and Delaware combined. Although primarily in Wyoming (91%), 7.6% of the park is in Montana and the remaining 1.4% is in Idaho.

John Colter, a member of the Lewis and Clark expedition of 1803–1806, was probably the first white man to visit and report on the Yellowstone area. At that time the only Native Americans living year-round in the area were a mixed group of Bannock and Shoshone known as "sheepeaters." In 1859, the legendary trapper and explorer Jim Bridger, who had been reporting since the 1830s about the wonders of the region, led the first government expedition into the area. The discovery of gold in the Montana Territory in...