Fig. 1. Locations of the ten study megacities in China, which fall into four regions: Western Region (Chengdu, Chongqing, and Xi’an); Central Region (Wuhan); Eastern Region(Beijing, Guangzhou, Nanjing, Shanghai, and Tianjin); and Northeastern Region (Shenyang). Unnamed dots denote the other 24 megacities or provincial capital cities in China.The classification of four regions is from “National Urban System Planning (2005–2020)”, released by the Ministry of Housing and Urban–Rural Development of China.