There's a book by Bill Bishop called The Big Sort: Why the Clustering of Like Minded Americans is Tearing Us Apart. I haven't read it, but from the following reviews - taken from the Amazon.com site - it seems to be relevant to this thread. Nothing about folk music, though, as far as I know.

Mike

From Publishers Weekly
Pulitzer Prize–finalist Bishop offers a one-idea grab bag with a thesis more provocative than its elaboration. Bishop contends that as Americans have moved over the past three decades, they have clustered in communities of sameness, among people with similar ways of life, beliefs, and in the end, politics. There are endless variations of this clustering—what Bishop dubs the Big Sort—as like-minded Americans self-segregate in states, cities—even neighborhoods. Consequences of the Big Sort are dire: balkanized communities whose inhabitants find other Americans to be culturally incomprehensible; a growing intolerance for political differences that has made national consensus impossible; and politics so polarized that Congress is stymied and elections are no longer just contests over policies, but bitter choices between ways of life. Bishop's argument is meticulously researched—surveys and polls proliferate—and his reach is broad. He splices statistics with snippets of sociological theory and case studies of specific towns to illustrate that while the Big Sort enervates government, it has been a boon to advertisers and churches, to anyone catering to and targeting taste. Bishop's portrait of our post materialistic society will probably generate chatter; the idea is catchy, but demonstrating that like does attract like becomes an exercise in redundancy.

From Booklist
*Starred Review* How did zip codes become as useful to political activists as to mail carriers? In the relatively new cultural dynamics of political segregation, Bishop discerns a troubling transformation of American life. Complex and surprising, the story of that transformation will confound readers who suppose that recent decades have made American society both more diverse and more tolerant. Pinpointing 1965 as the year when events in Vietnam, Washington, and Watts delivered body blows to traditional social institutions, Bishop recounts how Americans who had severed ties to community, faith, and family forged new affiliations based on lifestyle preferences. The resulting social realignment has segmented the nation into groupthink communities, fostering political smugness and polarization. The much-noted cartography of Red and Blue states, as Bishop shows, actually distorts the reality of a deeply Blue archipelago of urban islands surrounded by a starkly Red rural sea. Bishop worries about the future of democratic discourse as more and more Americans live, work, and worship surrounded by people who echo their own views. A raft of social-science research underscores the growing difficulty of bipartisan compromise in a balkanized country where politicians win office by satisfying their most radical constituents. A book posing hard questions for readers across the political spectrum.