China's Commuting-Based Metropolitan Areas

Using commuting flows at fine geographic levels derived from cellphone location data, we provide the first delineation of China’s commuting-based metropolitan areas (MAs). Those MAs exhibit well-known system-of-city properties, but are substantively different from the official definitions of cities. We document several salient features. First, the overwhelming majority of commutes are short in both time and distance, and are confined within administrative boundaries. Consequently, commuting-based MAs rarely cross prefectural or provincial boundaries. Second, an MA’s size is highly correlated with its administrative hierarchy. Third, compared with countries of similar sizes or levels of economic development, China’s MAs are relatively small. We discuss several existing policies that may have contributed to these features. Finally, we provide practical recommendations for researchers who need to define Chinese cities as local labor markets but face constraints by the availability of statistics at fine geographic levels.