Hawai‘i, the Philippines, Guam—it wasn’t easy to know how to think about such places or even what to call them. At the turn of the twentieth century, when many were acquired (Puerto Rico, the Philippines, Guam, American Samoa, Hawai‘i, Wake), their status was clear. They were, as Theodore Roosevelt and Woodrow Wilson unabashedly called them, colonies.

Yet that spirit of forthright imperialism didn’t last. Within a decade or two, after passions had cooled, the c-word became taboo. “The word colony must not be used to express the relationship which exists between our government and its dependent peoples,” an official admonished in 1914. Better to stick with a gentler term, used for them all: territories.

It was gentler because the United States had had territories before, such as Arkansas and Montana. Their place in the national firmament was a happy one. The western territories were the frontier, the leading edge of the country’s growth. They might not have had all the rights that states did, but once they were “settled” (i.e., populated by whites), they were welcomed fully into the fold as states.

But if places like the Philippines and Puerto Rico were territories, they were territories of a different sort. Unlike the western territories, they weren’t obviously slated for statehood. Nor were they widely understood to be integral parts of the nation.