How Much Land Can Be Included in a National Monument?—Analyzing the “Smallest Area Compatible" Requirement in The Antiquities Act

The Antiquities Act gives the president the power to designate “objects of historic or scientific interest” as “national monuments.” Presidents have used this power expansively, protecting massive tracts of federal land, often by claiming that very large things, such as the Grand Canyon or even entire landscapes, are “objects” in the requisite sense. There is legal debate over such uses of the Act, with critics arguing that they depart from the original intent and meaning of the legislation. What has been less discussed, however, is whether the Act allows presidents to protect just the object of interest (whatever it turns out to be), or whether it allows presidents to protect a substantial amount of land around objects of interest. I draw from language in the Antiquities Act and existing case law to argue the latter. Due to the nature of “historic and scientific interest,” protecting an object with such interest often requires protecting certain features of the broader landscape. This holds regardless of what counts as an “object of interest.” As a result, it offers a way to argue on certain critics’ own grounds for more expansive designations: even granting a narrow, originalist conception of what qualifies as an “object,” large designations can be justified.