Americans sorting themselves into politically similar counties

Corey Lang, assistant professor of environmental economics, and Shanna Pearson-Merkowitz, associate professor of political science, sought evidence for claims made in the 2008 book The Big Sort that suggested that people were choosing to live in politically segregated communities where Republicans and Democrats had little interaction with each other. Many academics disagreed with author Bill Bishop's hypothesis, so Lang and Pearson-Merkowitz decided to test it.

They examined data from presidential elections for every county in the country from 1976 to 2012, scrutinizing how voter support for political parties changed from one election to another. What they found in the 1970s and 80s was the reverse of what The Big Sort predicted.

"It was a complex story back then. The data suggest that counties were becoming more politically competitive," said Lang. "In some cases counties were even switching parties."

Beginning in 1996, however, partisanship began to increase and counties became more and more politically polarized. During the last decade, there has become less and less political competition in most counties.

"The political parties are competitive on a national level, but on a county basis there are fewer and fewer counties up for grabs," said Pearson-Merkowitz. "And each election we're seeing more polarization."

According to Lang and Pearson-Merkowitz, the increase in competitiveness that occurred in the 1980s and early 1990s was due to the dramatic change that occurred in what the parties stood for. The Democratic Party solidified its position as the party of Civil Rights, labor unions, and abortion rights, while the Republican Party became increasingly conservative on a host of issues.

"That party change made it look like we were living in more diverse counties, but no one actually moved," Pearson-Merkowitz said. "Instead, as the political parties figured out what their positions were, people decided what parties to associate with. The places are politically the same as they used to be."

For example, Democratic counties in the South in the 1960s were Democratic because that was the party that was more conservative. Those same people are now Republican because it is now the conservative party.

An examination of IRS data showing voter movement from one county to another suggested that migration did not play a role in the shifting levels of party support. Both professors agree that this increasing polarization is worrisome.

"It's good for the country for people to be exposed to a diversity of political opinion and party identifications," Lang said. "But it's concerning when there is such a disconnect between locations that rural Texans cannot even understand New Yorkers because they never hear the other's perspective."

"And when we see regional polarization, we're likely to see an even greater polarization in government," added Pearson-Merkowitz. "Being elected by an area that's more and more one-sided means there's little reason to compromise. It also means there will likely be less turnover among elected officials. But competition and turnover is healthy for a democracy."

This increasing polarization is happening at the same time that the highly partisan television news channels became popular, like Fox and MSNBC.

"Now, not only are people living in more politically homogenous areas, but the news they watch is homogenous," Pearson-Merkowitz said. "So not only are they not getting different views from their neighbors, they're not even hearing different views from the news. And that's likely to produce a very intolerant population because they have no exposure to the other side."

So while the researchers say "the big sort" is happening, it is not occurring from selective movement of voters to communities of similar political perspectives.

"People are not necessarily moving, but places are becoming more entrenched in their partisanship," concluded Pearson-Merkowitz. "We're becoming more blue and red and less purple, and that's concerning to me."