This is a great discussion. In a July blogpost about trade, Krugman pointed out that the Fed ensures full employment through monetary policy. He failed to recognize, however, that monetary policy affects the economy mainly through asset prices these days, meaning that it benefits areas that are home to a lot assets, i.e. metropolitan areas. Monetary policy thus contributes to the polarization between regions. http://krugman.blogs.nytimes.com/?s=trade