Here's a political map that's new to me, devised by Robert David Sullivan of the Concord Monitor for an organization called MassINC. Sullivan has divided the country into 10 regions, each of which cast about the same number of votes for president. The regions aren't all contiguous, and some of them don't make much sense to me: Chippewa contains Pittsburgh and Cleveland to the east and central Iowa to the west, but not Detroit and Chicago, which are in Mega-Chicago. George W. Bush carried five of the regions in 2004: Comanche (63 percent), Cumberland (60 percent), Frontier (58 percent), Southern Inland (57 percent), and South Coast (53 percent). John Kerry also carried five of the regions in 2004 (I've given Bush percentages so as to make these figures commensurate with those above): Upper Coasts (38 percent), Northeast Corridor (39 percent), Mega-Chicago (45 percent), El Norte (48 percent), and Chippewa (48 percent).
Sullivan has calculated the number and percentages for Hillary Clinton and Barack Obama in primaries and caucuses in each of his 10 regions (where caucus results are available). He notes that Clinton has been "cleaning up" in counties where Bush improved his percentage most between 2000 and 2004 and that Obama has been running strongest in areas where Bush's percentage was lower in 2004 than in 2000. The reason is that Clinton has been running well in areas with many white ethnics, Jacksonians and Latinos—the groups among which, as I showed in my introduction to The Almanac of American Politics 2008, Bush most improved his percentage in 2004. And Obama has been running strongest among blacks and upscale whites, groups which tended not to give Bush higher percentages in 2004 than in 2000.
Curiously, Obama is carrying only three of Sullivan's 10 regions: Mega-Chicago, South Coast, and Southern Inland. (By most scorecards he's won more popular votes, but Sullivan shows him with slightly fewer, presumably because he couldn't assign caucus votes to counties in some states.) The highest percentage for either candidate is Clinton's 55 percent in El Norte.