In a broad attack on America’s natural heritage, President Trump signed an executive order to review several national monuments—with an eye toward opening up these public lands to extractive activities such as oil and gas drilling. Trump directed Interior Secretary Ryan Zinke to look at all areas that have been declared monuments over the past 21 years, then recommend whether to shrink or eliminate the protections for those areas, which previous presidents felt were worthy to conserve under the 1906 Antiquities Act. Of particular focus are two monuments in Utah—Grand Staircase-Escalante (established by President Clinton) and Bears Ears (established by President Obama)—but Trump’s order encompasses more than 50 others, covering hundreds of millions of acres that capture our country’s natural and cultural heritage. This is an unprecedented attempt to roll back the clock on land protection, with no president ever trying to revoke another’s monument designation. Indeed, a president does not actually have the legal authority to do so.