After a year trapped in quarantine, summer travelers are getting outside to be in nature. National parks are experiencing, as expected, long lines of RVs and backpackers aiming their eyes and cameras at expansive desert vistas, tranquil alpine lakes, and abundant wildlife—apparently timeless scenes apart from human manipulation.

The naturalness of national parks, however, is more an artifact of National Park Service policy than many visitors realize, which means that management priorities are subject to periodic changes. That is to say, what we see in the national parks are products of history, of people and politics, and not just of geology and evolution. Like any political agency, the National Park Service responds to evolving public desires. And like any bureaucracy, it resists change.

Almost six decades ago, however, the agency shifted significantly in a short time-span. The catalyst for the change originated in a public relations disaster in Yellowstone National Park concerning the killing of elk on or near park land. An advisory board appointed to investigate and recommend alternatives produced a report that prompted a thorough reconsideration of Park Service practices around elk. The board reoriented park philosophy in ways that appeared more ecological, more natural.

Despite promoting biological principles as a guiding force, the new policies rested on flawed assumptions about the parks’ entwined human and natural histories. The policies required managers to, so to speak, intervene in the landscape, which ensured ongoing public controversies. Reckoning with this history can help us tease apart the human values that have shaped—and continue to transform—the captivating scenes in national parks.

Yellowstone, the nation’s first national park, owes its existence primarily to the area’s unusual scenery—geysers, colorful hot springs, waterfalls plunging into deep gorges. The enabling legislation for the park directed the Secretary of the Interior to retain the “natural condition” of the area’s wonders. Beyond preserving the scenery, Congress also prohibited the “wanton destruction” of Yellowstone’s wildlife.

Today, visitors to Yellowstone regularly observe bison, elk, deer, bears, and perhaps wolves, but this was not foreordained. The historian Paul Schullery has written about how, in the years surrounding its creation, Yellowstone faced an “ecological holocaust” from the profligate hunting of wildlife. Multiple accounts from the 1870s, for example, tell of thousands of elk being killed in the area. In the 1880s, hunting in the park was prohibited, making the park not only a scenic wonderland, but also, effectively, a game preserve.

Yet Yellowstone National Park sits within a larger ecosystem, and wildlife do not respect administrative boundaries. Yellowstone did not provide ideal elk habitat year-round. Biologists understood early on that, in the winter, most of the elk migrated to (sometimes distant) lowlands where more forage was available. Changes on the land by the turn of the twentieth century complicated elk migration as herds found their historical pathways blocked by domestic livestock and fences on the growing number of ranches in the valleys surrounding the park. For some elk, this journey spanned hundreds of miles, all the way from northern Wyoming to western Utah.

Hampered in their movements, the elk stayed closer to Yellowstone in high-elevation environments less suited for winter range. Almost simultaneously, the elk’s range shrank, the animals packed together, and food became scarce. Elk helped themselves to ranchers’ hay supplies, becoming an expensive nuisance. Local states tried to accommodate the constrained range and starving elk, and eventually the federal government intervened by providing money to purchase hay to feed the starving animals. In 1912, the federal government also bought land to create the National Elk Refuge in Jackson Hole, Wyoming.

The refuge did not solve the problem, however. The winter feeding of elk, which became routine at the refuge and elsewhere, including in Yellowstone, sustained regional herds at levels higher than the natural forage could support. By the time the biologist George Melendez Wright surveyed wildlife in the national parks in the early 1930s, Yellowstone’s ranges were in an awful state because of apparent overgrazing.

Wright called for larger parks to accommodate wildlife’s year-round needs more adequately, to support biological research more fully, and to minimize managerial interference by the Park Service, such as winter elk feeding or predator extermination. Wright saw a new path for the Park Service, but his death in an auto accident in 1936—and the arrival of World War II—shuttered the vision.

Meanwhile, pressures outside Yellowstone National Park kept concentrating the elk. These pressures included not only higher human populations and rural development, but also a notorious firing line of hunters who stood outside park boundaries in wait during hunting season, incentivizing elk to remain within Yellowstone’s borders. Such circumstances exacerbated the problem of the number of elk outpacing the carrying capacity of the range. Signs of overgrazing were obvious. The Park Service believed it could sit idly by no longer.

The National Park Service directed the killing of some 5,000 elk from the northern Yellowstone herd during the 1961 winter, leaving the agency under a cloud of disrepute. At the time, commentators invariably called it a slaughter. And who could argue with the characterization? In the sacred space of the nation’s public lands, such an act announced a certain disaster, but the Park Service indicated that “direct reduction”—a euphemism for killing elk—would resume the following year, a sure bet to worsen the public relations debacle. Secretary of the Interior Stewart Udall did what government administrators instinctively do: he impaneled an expert board to review policies and recommend changes.

Udall placed A. Starker Leopold in charge of the advisory board. Leopold was the oldest son of Aldo Leopold, a notable conservationist and author of the classic A Sand County Almanac. A zoologist long associated with the University of California, Berkeley, A. Starker Leopold brought familial and professional backgrounds in wilderness and wildlife to the advisory board. In the 1950s, he developed a knack for translating scientific ideas into clear language for public discussion and policy purposes.

Leopold synthesized others’ studies and became “a public educator par excellence,” in historian Kiki Leigh Rydell’s words. The group of scientists Leopold knew and worked with reconsidered predator-prey relations and wildlife habitat needs and conducted experiments with prescribed fire. This intellectual milieu encouraged Leopold, if trials demonstrated improve outcomes, to advocate sometimes unusual and unpopular policies if trials demonstrated improved outcomes.

Bringing that attitude to national park wildlife policies, Leopold and his colleagues broke new ground. The 1963 report’s official title was the mundane-sounding “Wildlife Management in the National Parks,” but it is known most everywhere as the Leopold Report. In the report, Leopold explained that, for most of its history, the National Park Service primarily focused on protection. It protected wildlife by prohibiting hunters and killing predators and protected resources by extinguishing fires. The protection approach was now insufficient for parks, Leopold wrote.

Instead, the proper goal of parks should be to maintain “biotic associations within each park” or, “where necessary,” recreate them, so that parks appeared “as nearly as possible in the condition that prevailed when the area was first visited by the white man.” To Leopold, “[a] national park should represent a vignette of primitive America.” This new framework did not center the visitor experience or parks’ spectacles, but focused instead on ecological processes. To be sure, this perspective included more than a little arbitrariness, as well as blind spots.

The Leopold Report established as normative the moment when Euro-American explorers or colonists found a place, but this choice was essentially arbitrary, overlooking and minimizing all the ways Indigenous peoples and their activities over millennia created the “vignette” Leopold wished the Park Service to re-establish. And many of the parks were carved out of Natives’ lands. Leopold may also have overestimated the agency’s and the public’s willingness to accept more human tinkering in the parks.

The Leopold Report is often associated with the Wilderness Act, signed into law 18 months later. Both were cornerstones of the 1960s’ zeitgeist around public land reform, which leaned toward ecology. Where the Leopold Report aimed to preserve (or recreate) biotic associations, the Wilderness Act aimed to preserve wilderness, defined as “an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain.”

At first blush, these may seem compatible or complementary impulses, but in response to the Leopold Report, Howard Zahniser, who authored the Wilderness Act and lobbied for it as executive secretary of the Wilderness Society, groused that wilderness needed “guardians not gardeners.” The Leopold Report, Zahniser worried, would send too many managers scurrying into the parks doing unnatural, unwild, and unwise things.

The Leopold Report produced new practices in the national parks, flowing out of its novel philosophy of restoring and maintaining ecosystems. Perhaps the cheapest, easiest, and most powerful tool for restoration was fire, and park fire policy immediately came under revision. Forest fires had been rigorously suppressed as a matter of government policy for decades, and the government removed traditional burning practices from the land along with Native peoples.

But cracks in the consensus around fire suppression had been widening, led by Harold Biswell, Leopold’s Berkeley colleague, who had recognized the central role fire played in many forest ecosystems. Biswell had experimented with introducing fire in national forests and found improved ecological functioning. Building on those insights, the Park Service in 1968 revised its fire regulations, allowing wildfires to continue under certain circumstances. The same year, the agency also deliberately set fires in Sequoia & Kings Canyon National Parks. If budgets were examined, it was clear that fire suppression still ruled as policy, but the Leopold Report helped rationalize the agency’s evolving view of fire and develop an alternative direction.

But the problem that initiated the Leopold Report concerned wildlife. If feeding elk in the winter seemed unnatural, and if killing elk by the thousands was unpopular, what was the Park Service to do? The answer the agency devised was called “natural regulation,” which might be likened to abandonment. Under natural regulation, the Park Service allowed winter conditions, predation, and habitat to determine elk survival, even if that meant mass starvation. The Leopold Report did not prohibit killing elk or other management methods, but the Park Service decided that “direct reduction” was too interventionist.

And so, elk numbers grew. By 1981, the northern Yellowstone herd was more than double the size it had been two decades before, when five thousand were killed. Scientific consensus proved elusive, but critics argued that these ballooning and often erratic numbers were causing degrading, and perhaps permanent, effects on the range. In 1995, wolves were reintroduced into the park after half a century, an act that helped meet the Leopold Report’s goal of reestablishing biotic associations. Wolves preyed on elk and changed the herd’s behavior, so that rangeland conditions and wildlife populations noticeably transformed. The ecological changes after wolf reintroduction, as well as the social and political ramifications, are still unwinding.

That unfolding is itself an important reminder and perhaps a key legacy, albeit an unconscious one, of the Leopold Report. Leopold’s “vignette” language suggested a snapshot frozen in time, and underplayed or misunderstood the profound ways Indigenous peoples created the contact-era ecosystem—with their fires, through their hunting, by living on all the continent’s lands. Nevertheless, by promoting biotic associations that would prioritize preserving ecological processes, the Park Service following the Leopold Report developed practices that guaranteed change.

In 2012, the National Park System Advisory Board’s Science Committee published a report, “Revisiting Leopold: Resource Stewardship in the National Parks.” If the Leopold Report emerged at a time when something like preserving naturalness dominated Americans’ thinking, “Revisiting Leopold” reflected a new era when accommodating change had arrived. National parks were not static “vignettes,” frozen in long-ago relationships but manifestations of “a dynamic and continuously changing system.” This report was meant to move beyond the Leopold Report’s shadow.

The Leopold Report originated to examine a relatively narrow policy, but Leopold moved beyond his brief. By contrast, the 2012 report began expansively, rooting itself in a compounding set of challenges from climate change and habitat fragmentation to an “increasingly diversified, urbanized, and aging” constituency. Signaling that this latter point was not merely formulaic rhetoric, one of its first findings declared that the national parks cannot be divided between “natural parks” and “cultural parks,” noting that Yellowstone’s wildlife constituted a cultural resource every bit as much as a natural one. The report recommended that the Park Service’s overarching approach ought to be to steward resources for “continuous change… in order to preserve ecological integrity and cultural and historical authenticity.”

It will not be simple, but humans and nature are tightly bound together. We seem well beyond preserving a “vignette of primitive America.” In our age, an era confronting climate change and questions of justice at every turn, it will be necessary for the National Park Service and the touring public to remember that these lands have been, since time immemorial, a human responsibility.

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