This month marks the 119th anniversary of the Antiquities Act of 1906, the law that allows presidents to designate national monuments. As both President Donald Trump and the current Republican-controlled Congress look to chip away at protections for federal public lands, including national monuments, the law has come under renewed scrutiny.
What is the Antiquities Act, and what does it do?
The Antiquities Act was passed by Congress and signed into law by President Theodore Roosevelt on June 8, 1906. Since its passage, all but three presidents have used its authority to designate 138 national monuments (the outliers being Richard Nixon, Ronald Reagan, and George H.W. Bush).
Susan Ryan, Vice President of Research at the Crow Canyon Archaeological Center in Cortez, CO, says the Antiquities Act allows presidents the ability to protect significant parts of the country's heritage.
"In a nutshell, the act gives the president broad authority to determine which aspects of our nation's heritage are valuable and worthy of protection," she said. "These can include cultural, historic, natural and areas of scientific value."
She said its passage came after an extended period of westward expansion by white settlers in the late 1800s, which led to the destruction of cultural and natural resources.
"It was the very first archeological law in our nation and the foundational law which protects archeological sites, both historic and pre-Hispanic," she said.
Over the century it's been in effect, the law has remained in the public conversation, and has been the subject of controversy. Ryan says there are three main reasons for that. The first is that it's a purely executive action, and some say it's too much power for the president.
"When we think about the difference between our national parks and our national monuments, a national park is created, modified, or revoked by an act of Congress," she said. "Whereas (with) a national monument, there is unilateral decision-making by the president who does not need Congress for that authority, nor does the president have to involve stakeholder input on that decision- making process."
The second reason is that there are no guardrails on how big or small a monument can be.
"A national monument can be one acre, or it can be 1.35 million acres or more," Ryan explained. "There is no consideration around the boundaries of what it would take to conserve and preserve our cultural, historic, natural, or areas of scientific significance. Therefore, there are presidents who are very conservative in how they create boundaries around these special places, and there are presidents who expand it beyond, to a landscape level, as opposed to an object level."
The third reason is that though the law gives the president broad authority to designate national monuments, it doesn't say that a president can reduce the size of, or rescind a monument designation altogether. This has led to what Ryan calls a "yo-yo effect" on two national monuments in Utah: Grand Staircase-Escalante, established by Bill Clinton in 1996, and Bears Ears, established by Barack Obama in 2016. The first Trump Administration shrank the monuments by 47% and 85%, respectively. Joe Biden restored both monuments to their original sizes in 2021.
What is the Trump administration trying to change about the Act?
The idea that a president can designate a monument but cannot revoke or diminish one is at the heart of a recent opinion from the Trump administration's Department of Justice (DOJ). The opinion addresses two recently established monuments: Chuckwalla in Southern California, and Sáttítla Highlands in Northern California, both of which were designated by Joe Biden in January 2025.
The primary legal basis for that is a 1938 DOJ opinion, which has said that monuments are irrevocable, once designated. The June opinion disagrees.
"We think that the President can, and we should," it reads.
It says that presidents have used the Antiquities Act to "withhold vast swaths of the American land- and seascape from potentially beneficial economic use."
It also criticizes the use of the Antiquities Act to designate national monuments at the landscape scale.
"There is no principled distinction between determining that one object is not worth protecting or all of them—and, by operation of law, no reasoned distinction between reducing and eliminating the parcel."
Steve Bloch, the legal director at the Southern Utah Wilderness Alliance, said this is not legally binding—it's just the DOJ's opinion on the issue.
"Trump asked if he has authority to rescind or diminish national monuments, and of course they gave him the answer he's looking for, which is 'yes, you do,'" he said. "So on the one hand, not surprising to see that. On the other hand, this does a 180, or goes entirely opposite on what the federal government and legal scholars and the courts have said for more than 100 years."
How are Westerners reacting?
Reducing national monuments is a deeply unpopular proposition for Western voters, according to polling. According to Colorado College's Conservation in the West Poll, support for keeping monuments designated over the last decade is popular across party lines in eight Western states, with 88% of all voters surveyed agreeing that designations shouldn't be revoked. That includes 83% of Republicans surveyed, and four out of five self-identified MAGA Republicans.
In Colorado, 92% of voters surveyed agreed with keeping recent monument designations in place, along with 82% of Utahns and 80% of Wyomingites.
Bloch, with SUWA, says Utah politicians' support for reducing monument designations goes against their constituents' wishes.
"We know the Utah politicians, Senator (Mike) Lee, Senator (John) Curtis, Governor (Spencer) Cox, acting against the interests of their own citizens and stakeholders, are egging the president on and saying that the monument should be undone," he said. "So we're prepared for the worst. We will challenge any decision by the president to dismantle the Grand Staircase-Escalante and Bears Ears monuments, and we expect to prevail in court. We think that those decisions… would not be well-founded in law."
Will Roush, the executive director of western Colorado-based Wilderness Workshop, says seeing the decision from the DOJ emphasizes the need to seek other avenues to protect important landscapes.
"I do think it does reinforce the real value of those most durable protections," he said. "Things like wilderness, Wild and Scenic rivers, those are the gold standard of public lands. And I think these attacks—whether it's the sale of public land or the attacks on national monuments—really reinforces the value of that permanent congressional protection, in all its different forms, and we need to redouble our efforts to do that."
Susan Ryan, with Crow Canyon, worries about the impacts this will have on relationships between the U.S. government and Indigenous nations, particularly in the West. For national monuments like Bears Ears and the recently designated Chuckwalla National Monument in Southern California, federal agencies like the Bureau of Land Management enter into agreements with local tribes to co-manage the lands within the monument.
At Bears Ears, the coalition consists of five tribes: the Navajo Nation, Hopi, Ute Mountain Ute, Ute Indian Tribe of the Uintah and Ouray Reservation, and the Pueblo of Zuni.
Ryan said that by diminishing or undoing these monuments, it's taking away an important voice from people who have stewarded these landscapes for time immemorial.
"We're saying that the importance of their co-management strategies on these lands and their sacred ways of looking at the lands, their traditional knowledge, is also not as important or valued or respected as the need for public lands to be used for extractive industries or for other activities such as grazing or recreation," she said.
"So in a way, we're diminishing those trust relationships between sovereign nations and the United States government by not inviting them to discussions as we modify or revoke national monument status."
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