The outline of the United States is a familiar shape. It’s an image that’s imprinted itself around the globe as westward expansion formally defined the American mainland with the incorporation of Arizona and New Mexico in 1912.

But as historian Daniel Immerwahr argues in How to Hide an Empire, that familiar map obscures more than it reveals. Of course, that map omits its two newest states, Alaska and Hawaii, located hundreds and thousands of miles from the mainland. But it also excludes our enduring colonies, like Puerto Rico and Guam, as well as the countless military bases, unincorporated territories, and formerly occupied lands to which America once laid claim.

By failing to think of these spaces when we think about the United States as a country, Immerwahr argues, we can’t comprehend many important moments in US history.