According to Colin Woodward, author of "American Nations: A History of the Eleven Rival Regional Cultures in North America," America is simultaneously getting more diverse and more polarized because we are "self-sorting", consciously choose to live in communities which reflect our political and cultural values. I have personally witnessed this in my own life as people I know lament where they are living due to its politics and culture, not due to jobs or crime or climate or any of the more traditional reasons. There seems to be less and less e pluribus unum going around these days. Read an excellent review of the book HERE which is also my source for the information here. *NOTE: click on the map for a closer inspection.