1887 Tourists pose on Glacier Point above the Yosemite Valley. IMAGE: LIBRARY OF CONGRESS
Though it was inhabited by Native Americans for thousands of years, the area of the Wyoming and Montana territories known as Yellowstone was not mapped in detail until the late 1860s.
After an 1871 survey documented the space’s stunning natural beauty and unique geological character — perched atop the largest supervolcano on the continent, the area contains half of the world’s geothermal features — Congress was persuaded to protect the region from development and set it aside as the first national park.
Other national parks were soon dedicated in turn, including California’s Yosemite National Park in 1890. Tourists and adventurers drawn by photographs of dramatic peaks, valleys, waterfalls, lakes and geysers, flocked by rail, car and horse to these early preserves.
By 1916, there were some 35 national parks and monuments, all of them managed by either the Department of the Interior, War Department or Forest Service.
To organize the protection and preservation of these spaces for generations to come, President Woodrow Wilson signed an act on Aug. 25, 1916 creating the National Park Service, bringing all of America’s “crown jewels” under the management of a single dedicated agency. Lots more here: The first visitors to America’s National Parks