[T]ake Philly out of Pennsylvania, the Big Apple out of New York, the Motor City out of Michigan, the Windy City out of Illinois, Cleveland out of Ohio, Milwaukee out of Wisconsin, St. Louis out of Missouri, etc., and a lot of blue states would instantly be red. What explains this pronounced and hugely significant partisan divide between urban and nonurban areas?

One obvious explanation for the overwhelming Democratic majorities in big cities is the Curley effect with the corresponding concentration of Democratic constituencies like welfare recipients and unions, but there is more to it than that. The Curley effect has turned once-vibrant cities into economic basket cases, but what, then, can explain the perennial dominance of Democrats in such thriving, prosperous cities as Boston, Chicago, and San Francisco? Why do affluent, white-collar, highly educated citizens in these cities tend to be liberal and vote Democratic?

Sociologists could have a field day with this question, but the explanation could be something as simple as the fact that people who live in cities are relatively insulated from how difficult and challenging it can be to produce the food, energy, equipment, devices, etc., that comprise the affluence that urbanites enjoy. In their urban cocoons, city-dwellers take for granted the abundance and availability of the economic goods that they consume. For instance, many well-to-do, educated urbanites see no downside to supporting stricter regulations and higher taxes on energy producers, because to them, energy is something that is always there at the flip of a switch (except during the occasional hurricane, as some New Yorkers recently discovered). Life in the city for affluent Americans creates the illusion that all they have to do is demand something and--presto!--it will be there when they want it.

Via What Explains The Partisan Divide Between Urban And Non-Urban Areas - Forbes.