Journalist Bill Bishop has been as close a student as anyone of the way Americans are increasingly living among their own kind – politically, as well as culturally.

His book, The Big Sort, pointed out the increasing tendency of Americans to live among like-minded people. Not surprisingly, when people move, they look for communities where they feel at home, whether that means living where people are concerned more with guns and cars or high culture and coffee shops. The result is that more and more people are living in counties that are either heavily conservative or much more liberal.

In 1976, only about a quarter of all Americans lived in what Bishop calls “landslide counties,” where one party’s candidate won by 20 percentage points or more. By 2012, more than half the country lived in landslide counties. When Bishop published his book, back in 2008, he argued that people may end up living among fellow liberals or conservatives, but it’s not as though they were checking out precinct-level voting data with their real estate agents. Instead, they followed cultural cues and the political sorting occurred as a by-product. At this point, Bishop, who lives in Texas and edits a website devoted to rural concerns called The Daily Yonder, is not so sure.

Our politics have become increasingly “tribal,” he notes, with people’s opinions on issues often shaped by the positions taken by the political team to which they swear allegiance.

Governing spoke with Bishop about this past November’s elections and what they tell us about polarization and how voters are sorting themselves. The interview has been edited for clarity and length..

What struck you about this fall’s elections?

Campaigns and candidates didn't seem to matter. That gets to the proposition that people were voting more for their identity than policy or anything else.

You had Wendy Davis running for governor in Texas. She had a ton of money and all the smarty pants from the Obama campaign running voter turnout. They did about as well as this guy running for agriculture commissioner, who didn't raise any money and didn't make any campaign appearances. It makes you think that the vote is more an act of self-expression than it is a vote that responds to policies or campaigns or individual turnout efforts.

So you think party-line voting has gotten stronger over time?

There's research that shows those tribal feelings have increased at the same time that straight-ticket voting has increased. The way Democrats view Republicans and Republicans view Democrats -- people now more likely to discriminate based on parties than on race, according to some studies.

In the early 60s, when you mentioned a Democrat to a Republican or a Republican to a Democrat, they weren't likely to think they're less generous or intelligent. Now, they're extremely more likely to think that, based on party affiliation.

In 1960, only 5 percent of Republicans and 4 percent of Democrats said they'd be displeased if their kids married someone from another party. YouGov asked the same question in 2010, you had half of Republicans and a third of Democrats saying they would be upset if their kids married someone from a different party. There was once only a slight bias against those from a different party. Now, people think they’re dumb.

Why do you think our politics have become so tribal?

My sense is that when you only have two choices, then the feeling against the other is stronger. Since the two tribes are so vividly identified, then it makes the sense of the ‘other,’ in quotes, stronger. That's reinforced by media that caters to one side or the other and our geography, when we're more likely to be around people like us.

Our allegiances are reinforced by everything we see and listen to. Our other forms of allegiance have dissipated -- allegiance to community or an occupation or a union or civic organization. Our party allegiance becomes a stronger way to identify ourselves.

It's a social identity more than anything else. As our other means of identifying ourselves have lost their hold, this one that remains seems to have gotten stronger. It's more akin to picking a sports team than it is to picking a policy. Once you pick a team, that's your party and that's your identity and that's who you vote for. If that takes over from policy or class or all those old markers of politics, you end up with the kind of politics that we have.

What does this fracturing of the electorate mean for governing, particularly when power is divided?

If the purpose of politics is actually to get things done and solve problems, then of course it's not working. But it seems that politics in a way is working. If the purpose of politics is to express yourself and to identify yourself, then what's happening in Congress is working.

The purpose of politics now is self-expression. Except locally, where things get done, where the majorities exist. A lot of interest groups focusing their efforts at that level, or the state level. You go to the places where you have the majority and work from there.