The United States has long enjoyed a unique position of economic supremacy. By the early 1990s, however, almost everyone believed that the age of U.S. supremacy was nearing its end. Circa 1992 few people would have dared to suggest that a second "American Century" might be in prospect. At the millennium, however, such suggestions are indeed being made. Several years of extremely favorable U.S. economic performance, all the more dramatic in contrast to some of the crises and setbacks elsewhere, have made it seem possible that American supremacy, far from being further eroded, will return to something like its early post-World War II levels. But can America really stay on top? To raise this question is not in any sense to accept the idea that the world economy is a zero-sum game; if America does well, this is not bad news for the rest of the world, nor is a renewed supremacy based on dismal performance elsewhere good for us. But it is still interesting to ask whether the special position of the United States in the world economy has gained a new lease on life.