The United States' share of the global economy has been remarkably steady through wars, depressions and a slew of rising powers. It was 32 percent in 1913, 26 percent in 1960, 22 percent in 1980 and 27 percent in 2000. With the brief exception of the late 1940s and 1950s—when the rest of the industrialized world had been destroyed—the United States has taken up about a quarter of world output for about 120 years and is likely to stay in roughly the same position for the next few decades if it can adapt to the current challenges it faces as well as it adapted to those in the past.I spent a good amount of time studying historical changes in the world balance of power in graduate school. One of the top scholars working in the global balancing literature is Christopher Layne. Layne's got a new piece in Fall 2006 edition International Security. Entitled, "The Unipolar Illusion Revisited: The Coming End of the United States' Unipolar Moment," Layne argues that America's preponderant world postition is expected to erode into a system of multipolar power by 2030.
Here's the key summary of Layne's argument:
U.S. hegemony cannot endure indefinitely. Even the strongest proponents of primacy harbor an unspoken fear that U.S. hegemony will provoke the very kind of geopolitical backlash that they say cannot happen (or at least cannot happen for a very long time). In fact, although a new geopolitical balance has yet to emerge, there is considerable evidence that other states have been engaging in balancing against the United States—including hard balancing. U.S. concerns about China’s great power emergence reflect Washington’s fears about the military, as well as economic, implications of China’s rise. Other evidence suggests—at least by some measures—that the international system is closer to a multipolar distribution of power than primacists realize. In its survey of likely international developments through 2020, the National Intelligence Council’s report Mapping the Global Future notes: “The likely emergence of China and India as new major global players—similar to the rise of Germany in the 19th century and the United States in the early 20th century—will transform the geopolitical landscape, with impacts potentially as dramatic as those of the previous two centuries. In the same way that commentators refer to the 1900s as the American Century, the early 21st century may be seen as the time when some in the developing world led by China and India came into their own.” In a similar vein, a recent study by the Strategic Assessment Group projects that by 2020 both China (which Mapping the Global Future argues will then be “by any measure a first-rate military power”) and the European Union could each have nearly as much power as the United States. Projecting current trends several decades into the future has its pitfalls (not least because of the difficulty of converting economic power into effective military power. But if this ongoing shift in the distribution of relative power continues, new poles of power in the international system are likely to emerge in the next decade or two.I enjoy Layne's scholarship, especially his deep engagement with the literature on diplomatic history. I don't find this article particularly compelling, however. He's got a good theoretical critique of the main arguments in favor of enduring, benign American unipolarity. He notes that this is a scholarship of great power exceptionalism, and it holds that the U.S. -- because of democratic structure and values -- will not likely meet the fate of other declining great powers in history. Unfortunately, Layne doesn't deeply address technological trends contributing to either the maintenance or erosion of American global economic and political leadership.
Layne notes that he was wrong about America's decline before (in his 1993 article, "The Unipolar Illusion"), and I think he'll be wrong again. In light of Zakaria's analysis above, I remain optimistic that the U.S. can sustain its global leadership position far into the future. We have been down the road of predicted relative decline before. Many analysts saw Japan overcoming the United States during the 1980s. Today, others see China and India outstripping America in the coming decades. But as Zakaria notes,
The genius of America's success is that the United States is a rich country with many of the attributes of a scrappy, developing society. It is open, flexible and adventurous, often unmindful of history and tradition. Its people work hard, putting in longer hours than those in other rich countries. Much of this has do to with the history and culture of the society. A huge amount of it has to do with immigration, which keeps America constantly renewed by streams of hardworking people, desperate to succeed. Science laboratories in America are more than half filled with foreign students and immigrants. Without them, America's leadership position in the sciences would collapse. That is why America, alone among industrial nations, has been able to do the nearly impossible: renew its power and stay at the top of the game for a century now. We can expand our science programs—and we should—but we will never be able to compete with India and China in the production of engineers. No matter what we do, they will have more, and cheaper, labor. What we can do is take the best features of the America system—openness, innovation, immigration and flexibility—and enhance them, so that they can respond to new challenges by creating new industries, new technologies and new jobs, as we have in the past.That to me sounds like an accurate assessment of America's future prospects.