The recent megalopolis stuff will also make things more complicated, though I'm unfamiliar with the fares for the regional HSR so I'm not sure that daily commut

The recent megalopolis stuff will also make things more complicated, though I'm unfamiliar with the fares for the regional HSR so I'm not sure that daily commuting from Nanjing to Shanghai actually makes a lick of sense. Even in the US, comparing by counties is dangerous, because counties are not standardized between states. Sometimes cities are contiguous with counties (San Francisco), sometimes they are smaller (Chicago), sometimes they are bigger (New York's 5 boroughs are each a county.)