Americans are good at remembering what they want to remember. The hall where Patrick Henry spoke, the Old North Church in which Paul Revere saw the lantern, the hall in which the Declaration of Independence was signed, the houses of Washington, Jefferson, Madison, Hamilton, and Franklin—all survive or have been painstakingly reconstructed. Their counterparts from the French Revolution have almost entirely vanished. The educational effort at Civil War battlefields overwhelms anything at any European field I’ve ever seen. (Although the soon-to-open visitor center at Waterloo looks almost Gettysburg-like in scale.)

But Americans are also good at forgetting. Antebellum sites that survived or were reconstructed after the Civil War are typically purged of their slave quarters. A project to mark the sites of every lynching across the American South exists only in cyberspace. Demolition and removal are every bit as essential as construction and preservation to the creation of a usable past. Nobody would vacation in Colonial Williamsburg as it really was. Civil War re-enactors omit the amputations.

Yet forgetting has costs.

In 1917-18, Americans fought as something less than the overwhelmingly dominant partner in a coalition effort—something they would not do again for the next century and counting. The next era of world politics, however, seems likely to resemble the world of 1900 more than that of 1950 or 1990: a world of multiple, mutually suspicious great powers grouped in uneasy coalitions defined much more by interest than ideology. As the United States joins with India, Japan, Korea, and Vietnam to balance China, the First World War era may offer more positive and negative guidance for the future than the era when the United States was more lopsidedly supreme.

President Truman looks like a more successful coalition manager than President Wilson because of his superior skills—but also because he had an easier job. When you’re paying everybody’s bills, it’s easier to get your way. The presidents of the 21st century, however, will likely feel that their challenges resemble Wilson’s more than Truman’s or Eisenhower’s or Reagan’s. Their allies will be less ideologically and culturally comfortable than Churchill’s Britain or the democracies of NATO. Their economic and strategic superiority will be less overwhelming.

And perhaps in the 21st century, the proposition that the United States stands as an exception to the norms prevailing everywhere else in the developed world will also look more doubtful. “American exceptionalism,” as Americans began talking about it in the 1950s, rested on a series of claims about American history. It was claimed that because America had never known a feudal aristocracy, the United States had evolved as a uniquely classless society, at least for its white citizens. Because America was classless, the United States was uniquely immune to socialism and communism. This achievement came at a price however: a society uniquely indifferent to high culture, uniquely characterized by mass production and mass marketing.