When President Trump proposed the United States should buy Greenland from Denmark this month, he unwittingly perpetuated a longstanding American trend of imperial-style territorial expansion. Alaska and the Louisiana Purchase were similar territorial acquisitions to the United States. The Danish Prime Minister promptly denied Trump’s offer, notwithstanding that the United States already maintains a military base in Thule, Greenland. Like in other territories, the indigenous people at Thule were expelled to establish the U.S. presence. These examples point to a bigger trend of American colonies that have existed for almost as long as the United States itself. After the Spanish-American war, the United States occupied Cuba, Puerto Rico, the Philippines, and many other territories. By the end of WWII, many became independent, but the United States still occupies large swaths of land for use by the military. These bases have massive economic, cultural, and social effects on the countries in which they reside. Northwest University historian Daniel Immerwahr recently wrote a book about all of this. It’s called How to Hide an Empire: A History of the Greater United States.