For the first time in a long time—when Ulysses S. Grant was president in fact—the US is no longer the largest economy in the world. That distinction now belongs to China, which will produce $17.6 trillion in goods and services this year, compared to $17.4 trillion for the US, according to the International Monetary Fund. As recently as 2000, the US produced nearly three times as much as China. This year, China will account for 16.5% of the global economy when measured in real purchasing-pow...