In recent decades, China has undergone the most dramatic urban migration in the history of the world, so you might be forgiven for thinking all that is required from urban planners is to "build it and they will come," so to speak. However, as the Western media often reports with much schadenfreude, China's unprecedented urban explosion has not come without a few missteps, and many new cities are widely claimed to be "ghost cities," empty of residents even as more gigantic apartment blocks are being built. Such stories are usually accompanied by anecdotes of empty public spaces and a rough count of the number of homes left in the dark at night, but little further empirical data. So exactly how underpopulated does a city have to be to be a "ghost city," and just how rife are such places in China?
As reported by MIT Technology Review, one Chinese web company has started looking for answers to just such questions. Baidu, effectively a Chinese version of Google, has used their "Big Data Lab" to investigate the commuting patterns of their 700 million users, establishing exactly which cities are dramatically underpopulated.