The impact of American culture abroad has become obvious to travelers, and not only a source of income for shrewd marketers of the nation’s consumer goods, but also, of course, a subject that has generated lively scholarly interest and a formidable bibliography. Whether in movies or in music, whether on television or on the internet, no nation in history has bestridden the planet as the United States has; and the political ideas emanating from the Declaration of Independence and the Bill of Rights have enjoyed an even longer (and more salutary) influence. For close to a century, the appeal of such a culture has been a force to be reckoned with; in recent decades, in much of the world, American programs and American products—enhanced by American power—have been close to inescapable. By now they are so often entwined with local habits and values that the foreignness of the New World has become internalized. During a recent visit to France, I noticed a teenager wearing a t-shirt emblazoned with the following slogan: Liberté, Egalité, Beyoncé. But how might the most striking qualities of American society be identified and understood? What are its laws of historical motion?