In 1997, the Chinese Communist Party designated the southwestern city of Chongqing as China's fourth "municipality," carving an area about the size of South Carolina out of Sichuan province. The purpose of the change was to transfer administrative control of the city from the Sichuan provincial government to the capital, enabling Beijing to better oversee the development of the nearby Three Gorges Dam project. Overnight, the Chinese government had created a conurbation of 28 million residents, leading Time magazine (among others) to label Chongqing "the world's largest city."

There was just one problem: Chongqing "municipality" has a lot of land that isn't, well, municipal: In addition to the city itself, Chongqing now includes outlying suburbs, satellite cities, and ample countryside. If we were to consider just the city's urban core, then Chongqing's actual population is closer to 5 million—still huge, but not the biggest city in China, much less the world.

Andrew Stokols

What accounts for the confusion? The answer lies in China's peculiar administrative divisions. First, there are ordinary provinces (like Sichuan, Yunnan, and Shanxi) which, like American states, have a parallel government structure to the central government. Then, there are "ethnic autonomous regions" (like Tibet, Xinjiang, and Inner Mongolia) which function like provinces and aren't, by the way, remotely autonomous. And finally, there are the municipalities: Beijing, Tianjin, Shanghai, and Chongqing, large cities governed directly by the central government. (Imagine if, in addition to Washington, D.C., that New York City, Chicago, and Los Angeles were "districts" rather than cities within states). Then, finally, are the special administrative regions of Hong Kong and Macao, but that's a whole other story.