Amid all the talk today about what sort of place Rick Perry comes from—and how much people there clung to their appellation of a certain piece of land —it's worth calling attention to what has to be one of the most telling and eye-opening maps of contemporary voting behavior.

In 2004, George W. Bush beat John Kerry with 50.7 percent of the vote. Four years later, Barack Obama beat John McCain with nearly 53 percent of the vote. But amid this decisive shift to the Democrats, something funny happened: in nearly a quarter of the counties in the country, McCain got a higher percentage of the votes while losing nationally than did his fellow Republican Bush while winning nationally four years earlier. And as this map shows, these counties make up a clearly defined swath of the country: a nearly contiguous band running from southwestern Pennsylvania, down through Appalachia and then curving west across the Upper South, picking up northern Alabama, northeastern Mississippi and nearly all of Tennessee, Arkansas, Oklahoma and Louisiana.

The arc crosses into Texas, where it encompasses much of East Texas and then peters out in southern and far western Texas -- but not before taking in the two counties in the news today. Haskell County, where Rick Perry grew up, went 64-36 for Bush over Kerry in 2004. Four years later, McCain won more of the vote in Haskell than had Bush, the former Texas governor running against a French-speaking windsurfer from Beacon Hill—66 to 33 percent. In adjacent Throckmorton County, where the Perry family hunting ranch with the unfortunate name is located, Bush thumped Kerry 76 to 23. But McCain did even better against Obama—80 to 20. Again, this is in the context of an election where most other places were going the other way—Texas as a whole went 61 to 38 for Bush against Kerry, but only 55 to 44 for McCain over Obama.

It is hard to dispute that the map tells a story about political geography and race. Obama did better among white voters overall than did Kerry. But he did signficantly worse with white voters across one whole swath of the country—a band encompassing Appalachia, the upper South and the oil-and-ranch country of the Southwest, a band that is predominantly white, Scots-Irish in ancestry and that is completing the same shift away from the Democrats that the Deep South made years earlier.

Rick Perry, of course, was one of the first to make that switch himself—he was so ahead of the curve when he jumped to the Republican Party in 1989 that his own county, Haskell, voted against him and for the Democrat when he ran for lieutenant governor in 1998. But his native ground has since caught up to him—and Barack Obama's candidacy helped accelerate the shift.