Is Donald Trump a fascist? It’s an interesting question that has generated insightful commentary over the past few months, with the best answers situating Trumpian illiberalism within America’s long history of racial oppression, slavery, Jim Crow apartheid, and the ongoing backlash to the loss of white privilege. But a key concept is missing from this discussion: empire. In particular, the way in which the end of the American empire—especially the exhaustion of its two most recent expressions, neoliberal economics and neoconservative militarism—has profoundly transformed its domestic politics.

One of the things that has made America exceptional—compared to other crisis-prone and class-conflicted countries—is that it has long enjoyed a benefit no other modern nation in the world could claim: the ability to engage in ceaseless, endless movement outward.

There have been many other empires, formal and informal. And many countries have something approximating a frontier. But in no other nation has the idea and experience of expansion been so integral to its nationalism: America, even before it its constitution as an independent republic, was conceived in expansion, its settlers exhibiting what Thomas Hobbes called an “insatiable appetite, or Bulimia, of enlarging Dominion.” From frontier settlement to post–Cold War neoliberalism and the drive into the Persian Gulf, there have been many different phases of this expansion. But through it all, the idea of America was predicated on a rejection of limits, on perpetual motion outward, on the seizing of territory, the opening of markets, and the grudging necessity of war to remove obstacles to the opening of markets. According to some tallies, since 1776, the United States has been at war 93 percent of its existence, passing through a mere 21 years of peace.

Since 9/11, critics of US foreign policy have mostly focused their analysis on blowback: on the way endless war produces endless enemies, which justifies endless war. Win win. But earlier, New Left intellectuals gave us another way to think about the relationship of foreign relations to domestic politics: how endless expansion—either through militarism or markets—helped defuse domestic tensions and allowed for the establishment of durable and stable institutions.

There were many different versions of this argument, but, as it pertains to the United States, its central idea is as simple as it is profound: Empire allowed the United States to avoid a true reckoning with the social problems, such as poverty, inequality, racism, crime and punishment, and domestic violence, caused by America’s brand of largely unfettered capitalism. ...