Steven Johnson on one of the impacts of urbanisation

'The problem with all the talk about Americans living in a country divided
between red and blue states lies not in the idea of division itself. The
problem lies in framing the whole issue around states. We do in fact live in a divided nation, but states are not the organizing principle we should use in thinking about the split. We are divided between the blue city and the red country... '

There's more on his site, www.stevenberlinjohnson.com