or more than a century, presidents have created national monuments to protect areas of historic, scientific, or cultural significance. But in December 2017, to expand fishing and mining rights, Republican President Donald Trump cut the size of Bears Ears National Monument and two other national monuments: Grand Staircase-Escalante in southern Utah and Northeast Canyons and Seamounts Marine off Cape Cod.
The move raised a key question: If a president can designate a national monument, can a different president take it away?
https://www.csmonitor.com/USA/Politics/2022/0125/They-shrink.-They-grow.-The-tricky-politics-of-national-monuments