The Polarization Express (washingtonpost.com)
I have argued that the spread of HOAs could contribute to political polarization because of niche marketing and the different relationship to public government. Here is a conference devoted to answering whether America is, in fact, becoming more politically polarized. The consensus, it seems, is "yes."

PRINCETON, N.J. -- The title of the conference held here last weekend, appropriately enough, included a question mark: "The Polarization of American Politics: Myth or Reality?" The 45 academics, politicians and journalists who gathered at Princeton University's Center for the Study of Democratic Politics never reached a vote, but all the evidence pointed toward the second alternative... James Gimpel of the University of Maryland and Bill Bishop of the Austin American-Statesman showed that "red" and "blue" voters are increasingly living in separate enclaves, with distinctive lifestyles, attitudes and partisan leanings shared among neighbors. To that extent, most of the conferees agreed, polarization is not just a phenomenon affecting politicians but something rooted in deeper social changes. Especially as sophisticated line-drawing for new congressional districts combines with the emerging pattern of like-minded voters living in geographical clusters, the latent divisions in American culture are made explicit on Election Day.