When the history of 2014 is written, it will take note of a large fact that has received little attention: 2014 was the last year in which the United States could claim to be the world’s largest economic power. China enters 2015 in the top position, where it will likely remain for a very long time, if not forever. In doing so, it returns to the position it held through most of human history.
Comparing the gross domestic product of different economies is very difficult. Technical committees come up with estimates, based on the best judgments possible, of what are called “purchasing-power parities,” which enable the comparison of incomes in various countries. These shouldn’t be taken as precise numbers, but they do provide a good basis for assessing the relative size of different economies. Early in 2014, the body that conducts these international assessments—the World Bank’s International Comparison Program—came out with new numbers.