China's Economic Rims ~ Supercity Megaregions

China has three so-called Economic Rims or supercity megaregions -- Bohai, Yangtze, and Pearl -- each agglomerations around a central megacity -- Beijing, Shanghai, and Guangzhou -- embracing upwards of a dozen smaller cities, all amidst geophysical supernodes -- Bohai Sea, Yangtze River Delta, and the Pearl River Delta. Each megaregion has populations between 50-100M and has colossal infrastructure and planning issues. This is epic and fascinating! P.S. It strikes me that Taiwan with it's economic miracle history should really be thought of as a superisland and thus fourth Chinese megaregion too!