How many megacities does China have? The United Nations puts it at six. Try 15.
China is urbanizing at a staggering rate—in 35 years, it has added more than 500 million people to its cities. As a result, it looks like the world has vastly underestimated the size and scope of growth in China's megacities, defined as those with more than 10 million people, according to a new report by the Paris-based Organization for Economic Cooperation & Development.
The research used analysis based on functional urban areas, rather than cities defined by administrative borders. Besides such better-known places as Shanghai, Guangzhou, and Beijing, the new list includes Harbin, a northeast city with a renowned annual ice and snow sculpture festival, and Nanjing, a former capital city that sits on the Yangtze River.
China's rapid economic growth, relative to the rest of the world, is one reason for the pace of urbanization, which has raised the living standards of millions of Chinese. And the bigger the city, the more each person produces in economic output, the OECD finds.
Size isn't everything, though. While you're more productive in the big city—er, megacity—the fastest economic growth by Chinese standards is happening in areas with populations of 1.5 million to 5 million people.
Rapid urbanization comes at a hefty price, however. Air pollution contributes to about 350,000 deaths a year in China, according to OECD estimates. Among the 112 Chinese cities included in the World Health Organization's Ambient Air Pollution in Cities Database 2014, only 22 are below the world average level of smaller particles.