Imagine that a version of the World Economic Forum was held in Davos four centuries ago. From across the globe, the great and the good of 1618 gather in the Alpine village: Chinese scholars in their silk robes, British adventurers in their doublets and jerkins, Turkish civil servants in their turbans and caftans. They have come together to discuss the great question of who will dominate the centuries ahead.

The Chinese point to their superb civil service and mighty navy. A Turk boasts that the Ottoman Empire is expanding westward and will soon hold Europe in the palm of its hand. A plucky Briton argues that his tiny country has broken with the corrupt, ossified continent and is developing dynamic new institutions, including a powerful parliament and a new sort of organization, the chartered corporation, which can trade all over the world. Yet in the entire discussion one region goes unmentioned: North America.

Four hundred years ago, North America was little more than an empty space on the map—an afterthought in educated minds and a sideshow in European great-power politics. The entire continent produced less wealth than the smallest German principality.

Today, the United States has the most powerful economy in the world: With less than 5% of the world’s population, it still accounts for almost a quarter of global GDP. America has the world’s highest standard of living apart from a handful of countries with small populations, such as Qatar and Norway. It also dominates the industries that are inventing the future—intelligent robots, driverless cars, life-extending drugs. The fact that 15 of the world’s top 20 universities are based in the U.S. according to the QS World University Ranking, suggests that it is well-placed to dominate the ideas economy.

The rise of the U.S. to economic greatness is an extraordinary story. But it is a story with a sting in the tail. Productivity growth in the U.S. has all but stalled in recent years. The number of new companies being created has reached a modern low. Geographical mobility has been in decline for three decades. Economists worry that America’s potential rate of growth—the pace at which annual output can expand without pushing up inflation—is also falling.