Re those red and blue counties again, some weeks ago, I posted the changing big-cities' shares of the U.S. population for various census years, 1900-2000. Those data showed an urbanizing population to about 1940 and a suburbanizing population since then. Exurbanizing-suburbanizing is probably more accurate.
The county-level employment data that I have only goes back to 1970. The decentralization story holds there too. Most commuting is now suburb-to-suburb.
I receive posts from a planners' listserv and the red-voting-county-exurban-suburban connection is a hot topic.
I assign David Brooks' "Patio Man and the Sprawl People" to my real estate development students. Patio Man is Brooks' exurban-suburban everyman, sketched with humor and insight. Yet, the humor derives from recognition and self-recognition. What the pundits (and politicians) are going to have to get used to is that the Patio Man demographic is growing -- and it does not conform to the hard-right ideologue image that pops up in all of the great-divide "culture wars" talk.