The National Park Service turns one hundred years old on August 25. Ideas about what is worthy of preservation as a national park have evolved over time, and today over half the sites the Service manages interpret some nationally significant person, place, event, movement, or idea in American history. Even large natural parks like Yosemite and Yellowstone often employ historians to study how humans have lived in, used, and affected the great natural resources the parks preserve. Americans invented the national park idea, and as the Service’s centennial birthday approaches, a review of what is so unique about it seems apt.

Many credit the artist George Catlin, famous for painting American Indians, with first articulating the national park idea. Catlin had great affinity for his subjects and worried (with good reason) that American westward expansion would threaten native cultures and the natural environment. These things might be preserved, he wrote in 1832, “by some great protecting policy of our government . . . in a magnificent park, a nation’s park, containing man and beast, in all the wildness and freshness of their nature’s beauty!” That same year, President Andrew Jackson signed legislation to set aside the hot springs of Arkansas Territory as a reserve for the future disposal of the United States. Congress failed, however, to follow up with any legislation to administer the site. More than thirty years later, on June 30, 1864, President Abraham Lincoln approved a bill transferring the federally-owned Yosemite Valley and Mariposa Big Tree Grove to the state of California so that they might “be used and preserved for the benefit of mankind . . . held for public use, resort, and recreation . . . inalienable for all time.”

It was the Yellowstone region of Wyoming and Montana that pushed the national park idea into the larger national consciousness. Numerous explorations of the area in the 1860s and 1870s led to published accounts of the region’s natural and geologic wonders, and many of the explorers agreed that the area should be set aside for public use rather than allowing it to fall under private ownership or commercial use. The Northern Pacific Railroad Company was, ironically, one of the Yellowstone’s biggest corporate boosters. Having a major tourist destination near its main line would, after all, be good for business. On March 1, 1872, President Ulysses S. Grant signed the act that made Yellowstone the world’s first national park. Other large natural parks, all in the west, followed over the next several decades, but the federal government created no agency to manage and administer them. Soldiers of the U.S. Army, including some African American “Buffalo Soldiers” were often deployed in the parks to prevent wildlife poaching.

While the first national parks were created to protect natural areas and resources, little was done to similarly protect sites of historic significance. In 1891, the Forest Reserve Act authorized presidents to proclaim permanent forest reserves on the public domain without congressional approval. Many argued that similar legislation was needed to set aside historically important areas, including several prehistoric sites in Arizona, New Mexico, Colorado, and Utah. It took years of wrangling, but on June 8, 1906, President Theodore Roosevelt signed the Antiquities Act, allowing presidents to declare “historic landmarks, historic and prehistoric structures, and other objects of historic or scientific interest” on federal lands as national monuments. Roosevelt was the most conservation-minded president in U.S. history, so his approval and use of the Antiquities Act fit perfectly with his own views on conservation and preservation. He created eighteen national monuments before leaving office in 1909, and presidents have created over one hundred others since the Act’s approval. Most recently, on June 28, 2016, President Barack Obama used the Antiquities Act to designate Stonewall National Monument in New York City, the nation’s first monument to the struggles and civil rights of the LGBT community. Nearly a quarter of the current units of the National Park System originated as national monuments via the Antiquities Act.

By 1916, the Department of the Interior oversaw a wholly western system of fourteen national parks, twenty-one national monuments, and two reservations–but still had no agency to manage them. The Army did the best it could, but soldiers had other missions and responsibilities. There was little official policy or guidance coming from Washington, D.C. about proper management of the sites, and conservationists bemoaned the parks’ vulnerability to people and entities less interested in conservation than exploitation. This concern proved prescient when the city of San Francisco was permitted to construct a dam in the Hetch Hetchy Valley in Yosemite National Park in 1913. John Muir and others fumed about “the rape of Hetch Hetchy.”

In 1914, Stephen T. Mather, a wealthy Chicago businessman and avid outdoorsman, complained to his friend, Secretary of the Interior Franklin K. Lane, about the mismanagement of the national parks resulting from the absence of a federal agency assigned the task. Lane invited Mather to come to Washington to try to solve the problem, and Mather eagerly accepted. Lane named him Assistant to the Secretary of the Interior for Park Matters in early 1915. Mather was a natural salesman and embarked on a furious public relations campaign that emphasized not just conservation of the parks, but also their economic potential as tourism draws. Publications like National Geographic ran articles supportive of a “national parks bureau,” and Mather sent copies of a beautiful publication called The National Parks Portfolio to members of Congress and other notable Americans. His plan worked: Congress passed legislation creating a National Park Service, and President Woodrow Wilson signed it on August 25, 1916. The bill directed the new agency “to conserve the scenery and the natural and historic objects and the wild life therein and to provide for enjoyment of the same in manner and by such means as will leave them unimpaired for the enjoyment of future generations.”

So the National Park Service has, since its inception a century ago, concerned itself with the future, both of the parks themselves and the people that will one day visit, learn from, and enjoy them. It would be another ten years before Congress created any national parks east of the Mississippi, and not until the 1930s would the Service—an agency always thinking about the future—take on the new challenge of preserving and interpreting America’s past in national historic sites, monuments, and parks.