National monuments are a direct result of the 1906 Antiquities Act, which gives presidents “the authority to, by proclamation, create national monuments from federal lands to protect significant natural, cultural or scientific features.” The Act also allows presidents to set aside or accept the donation of private lands for such purposes.

Without the protections and powers vested in the Antiquities Act, many of our most valued and beloved public lands would have been irreparably diminished, destroyed, or sold off to the highest bidder.

Today, President Donald Trump and Interior Secretary Ryan Zinke have their sights on reducing the size of, eliminating, and transferring ownership of lands within certain national monuments designated since 1996. About two dozen such designations remain in the cross hairs for further scrutiny, under this administration’s claims that they are too large, or that local communities weren’t sufficiently consulted or involved at the time of designation.

One wonders what Grand Canyon, Zion, Acadia and other national parks, all initially protected as national monuments, would look like today if earlier presidents had done what Trump would like to do with public lands belonging to all Americans.

In the mid-1880s, congressional attempts to protect the then Arizona Territory’s Grand Canyon from exploitation were defeated, yet in 1893 the canyon became part of a forest reserve established under President Benjamin Harrison. It stayed somewhat protected as part of a re-designated game preserve created by President Theodore Roosevelt in 1906. Using the newly granted powers of the Antiquities Act, in 1908 Roosevelt established by proclamation the 800.000 acre Grand Canyon National Monument.

For nearly a century now, the Supreme Court has upheld that there is no size restriction on national monuments. In Cameron vs. United States in 1920, it said that the president was free to protect a very large object of scientific or cultural interest-even if others had their eyes on the area for extractive or commercial purposes. That large area in question was The Grand Canyon.

Grand Canyon became a national park by act of congress under President Wilson in 1919. In 1975 President Gerald Ford signed into law an act of congress incorporating Marble Canyon National Monument (designated by President Lyndon Johnson) into an expanded Grand Canyon National Park.

Thankfully, the vast one-million acre Grand Canyon-Parashant National Monument, established in 2000 and bordering the national park to the northwest, is not under “review” by the Trump administration, but others in the Southwest such as Bears Ears and Grand Staircase-Escalante remain on the chopping block.

With the Grand Canyon and other significant places, it’s taken a steady, bi-partisan succession of administrations and congresses over time to build upon what others have protected and preserved before them. In 2017, it’s murky as to what kind of legacy the President and his Interior secretary envision when it comes to our public lands.

President Lyndon Johnson, over 50 years ago, said that “if future generations are to remember us with gratitude rather than contempt, we must leave them more than the miracles of technology. We must leave them a glimpse of the world as it was in the beginning, not just after we got through with it.”

This administration should use, and not curb, the authority of The Antiquities Act to protect more lands with significant natural, cultural and scientific features. It should designate more national monuments, and stop spending time and resources undoing the conservation legacies of others.

It should also stop fueling the myth that we already have enough, or more than enough public lands already. We should be doing everything possible to ensure that people long after we are gone can enjoy and experience a glimpse of the world as it was in the beginning, rather than after we got through with it.

If Trump’s and Zinke’s current efforts should prevail, we all become impoverished. Their efforts would likely not stop with undoing national monuments; public lands, regardless of their status and designation, would proceed to be sliced and sold off in piecemeal fashion.

Americans would surrender a freedom envied worldwide, the right to publicly access and enjoy these special places. Let’s not squander these amazing assets we all hold in common for the private, permanent gain of a few, while leaving future generations little to nothing of our natural heritage.