If politics today seems like a mud wrestling in a toxic-waste dump, we can find some meager comfort in the fact that things have been worse.

The Late Unpleasantness also known as the Civil War, bloody textile workers’ strikes and tenant-farmer revolts, that thing that happened on the Edmund Pettus Bridge — all these offer abundant evidence that Southerners are more than capable of expressing their political differences by beating the shit out each other.

The South has many tales of what historian Carl Degler called the “other Southerners” who challenged the party lines of their day and suffered for it. At the same time, ours is a region with a long and rich history of clamping down on political dissent. Southern historians have documented countless instances of such clampdowns. We’ve hounded college professors out of town for teaching any version of history that was not properly reverential about the mythical Lost Cause, we’ve vandalized the printing presses of anti-slavery newspaper editors, we’ve invoked an unwritten consensus called the Southern “way of life” to defy the federal government and the U.S. Supreme Court.

Still, up until the last quarter of the 20th century, divisions of politics, race and sub-regional differences in geography, culture, social class, accent, barbecue recipes and music could all be neatly packaged under a single shrink-wrap of born-again evangelical Protestant religion and regional pride. No matter what part of the South you came from, Southerners of my generation would have agreed that “Southerner” was a unifying concept (one celebrated in songs like “Are You From Dixie,” a 1915 song resurrected by Jerry Reed in 1969, and Johnny Cash’s “Hey, Porter.”)

But that was last century. Today, Southerners belong to tribes. The fact that you are reading this is most likely evidence that you are a member of a Southern tribe, called Bitter Southerners, which explicitly excludes certain Southerners. Just look at our manifesto: “If you are a person who buys the states’ rights argument … or you fly the rebel flag in your front yard … or you still think women look really nice in hoop skirts, we politely suggest you find other amusements on the web. The Bitter Southerner is not for you.”

As this statement implies, there’s a vast chasm between a typical white voter in, say, Baxter County, Ark., and his white counterpart in some in-town liberal enclave in Austin or Durham. Chances are that each will find the other culturally incomprehensible — and both of them will, in their own way, be culturally alien to the black voter in Coahoma County, Miss.

“The differences are ‘us’ and ‘them,’ and the ‘us’ and ‘them’ are Republican and Democrat,” Bill Bishop said to me in an e-mail recently. “People in some ways discriminate more today based on [political] party than on race.”

These days, there are plenty of conservative white Republicans in the South who would 10 times rather see their sons or daughters marry a person of another race — maybe even a person of another race and the same gender — than marry a person with liberal political beliefs.

“To me, when you say far-left liberal, that tends to imply certain value judgments that I may not necessarily share,” one Arkansas Republican Party functionary told me recently when I brought up that hypothetical question. “To have someone become part of your family….”

His voice trailed off; it was clear he found political intermarriage too distressing a concept to contemplate. And lest I sound judgmental, I should add here that if one of my daughters wanted to marry a fan of Rush Limbaugh or Sean Hannity, I’d feel the same way.

Tribalization is happening in the South so clearly you can see it on a map — or at least, you can see clues that it’s happening. A couple of years ago, I was doing research for a book on the 21st century South and what it was becoming. I was looking at presidential election returns by county, and ran across an article in "The Daily Yonder" (a website which Bill Bishop edits) talking about the counties that had flipped from Democratic to Republican, or vice versa, in the 2008 election. The interesting thing about the map to me was that all of the counties that flipped from Democratic to Republican were in the South — the upper South, specifically, starting in southwestern Arkansas and moving from there to west Tennessee and from there roughly up the Appalachians into western Pennsylvania.

Intrigued, I looked a little closer. What I wound up with was a list of counties which, in a historic Presidential election year featuring unprecedented voter turnout and the election of the nation's first black president, chose to march resolutely in the other direction and moved toward the Republican candidate by more than 8 points than four years earlier. Here’s what it looked like: