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, ... (full story)