Around the year 1830, the beauty of Niagara Falls, famous for its breathtaking scenery comparable to that of Europe's Alps, was already fading due to massive development. Scholars at the time were beginning to acknowledge the urgency of environmental conservation. In the early 1850s, the scenic wonders of Yosemite and Sierra Nevada, located in the western United States, started to become known to outsiders, and in 1864 the area was designated as a park. In the years that followed, the Goldrush of the West accelerated the fame of Yellowstone's beauty. In 1871 the US Congress appointed geologist Ferdinand Haydon to investigate the area and the Yellowstone National Park Act was passed. Finally, in March 1872 President Grant signed the Act, thus giving birth to the world's first national park. At the time of national park establishment, management of the park placed more emphasis on attracting more visitors than on nature conservation. However, there developed a gradual realization that without rigorous preservation of the natural ecology, not only was management of a national park meaningless, but users would soon become dissatisfied. The acknowledgment propelled the authorities administering the park to place priority on conserving the natural ecology. They realized that users would become more attracted to a park that best preserved nature.
According to the International Union for Conservation of Nature's (IUCN) definition, a national park refers to "a large area wherein one or more ecosystem is preserved, unimpaired by human development or occupancy, or an area wherein the inhabitant species, the geological location, or the traditional customs are subjects of keen interest to the public in terms of scholarship, education, and leisure, or an area which displays a remarkable natural scenery. The area must also be entirely controlled by a top ranking government organization which can exercise its power to prohibit any type of development or occupancy throughout the designated park area or to undertake any type of restriction or meaures required to effectively maintain the area in terms of preserving the ecosystem, geology, and the scenery.