"Is China, after a hiatus of 150 years, again the largest economy in the world? Not all sources of GDP data agree, but there is little doubt that China is either already now the largest economy, or it will, within a year, become so by overtaking that of the United States. Whichever the case may be, a long era when the American economy was the largest in the world and which began around 1860, is now reaching its end."

http://blogs.worldbank.org/developmenttalk/end-long-era