Income inequality has become one of the nation's hottest political issues, but it probably isn't talked about as much in Minnesota's Sixth District, currently represented in Congress by Michele Bachmann, a Republican.

It's not that this is a ­Republican-​leaning district and income inequality is an issue the Democrats are hoping to turn into votes this election cycle. Rather, it turns out that of all of the nation's 436 congressional districts, this is the one with the least amount of income inequality.

It's greatly tempting to see these two facts — a low level of income inequality and a conservative electorate — and conclude that one must have caused the other.

People looking for a partisan explanation likely won't find one, however, or at least one that nonpartisans would readily accept. Looking through the lens of economics doesn't help much, either.

It was Atlantic magazine that recently asked whether geographic differences in income equality could help explain partisan differences, just a small part of the raft of studies and commentaries on income inequality published this year.

In his report, the writer ranked all of the congressional districts in the country by the so-called Gini index, a basic measure of income inequality. A Gini score of zero means everybody has precisely the same income, and a score of one means that only one person got all the income in the district.

There were exceptions, of course, but the Atlantic was able to show that Democrats tend to serve districts with high levels of income inequality, while Republicans serve districts with relatively low income inequality.

The average Gini index for the country is about .454, or almost exactly the score for Minnesota's Fourth District, now represented in Congress by Betty McCollum, a DFLer. Other Minnesota districts were pretty close to average.

The clear outlier was the Sixth District, with a score of .385.

Those looking for a tidy explanation, said Larry Jacobs of the University of Minnesota's Humphrey School of Public Affairs, should be suspicious of any aggressively partisan one.

"Some people might look at that and say, 'Yeah, what did you expect, the Democrats are impoverishing their voters,' " he said. "Or conversely, you might have someone from the left saying 'What do you expect, Bachmann is keeping the wealth for the richer exurbs.' Both of those conclusions would be mistaken."

What's interesting is that level of income — how rich the folks in the district are — is not the most telling factor.

The Sixth runs across the northern Twin Cities suburbs and exurbs up through the St. Cloud area, and its per capita income is actually lower than in the district that encompasses the city of Minneapolis. And that urban congressional district, represented in Congress by DFLer Keith Ellison, is both the leader in income inequality in Minnesota and the most Democratic-leaning.

The Atlantic suggested that places with lower income inequality seem to vote Republican more because the issue of inequality may not rise to the level of social or political concern in areas where the people just don't see as much of it in their daily lives.

That explanation was posed more as a question than a conclusion, but it still did not play very well with Republicans such as state Rep. Matt Dean.

"That's insulting, come on, man," said Dean, who represents a part of the Sixth in and around White Bear Lake in the Legislature. "I don't think that people are trying to escape income inequality by moving into a Republican district, nor do I think that people there are ignorant of the plight of people with less income."

Dean has discussed how people choose places to live for cultural reasons with one of his close friends from high school, whom he described as a "really liberal guy" now teaching at a university in Virginia. His friend has been looking into attributes that may describe neighborhoods or districts with a lot of Republican voters.

Homeownership? The Sixth has the fifth-highest homeownership rate among all congressional districts.

Education? The Sixth has the 10th-highest rate among congressional districts for high school diplomas, but is nowhere near that high a ranking for the percentage of residents with college degrees. About 27 percent have a college degree vs. more than 43 percent in Ellison's Democratic-leaning urban district.

Wealthy? Not really, as the Sixth's per capita income is higher than the national average but lower than the statewide average. But only about 8 percent live below the poverty line, a far lower number than both the state and national averages. Not well off, but not poor, either.

What really sets the Sixth apart is its family structure, as it has the most residents under age 18 of all eight congressional districts in Minnesota.

When you consider that set of facts, you can understand why Dean said he advised his friend that the best places to find lots of Republicans are areas that are growing in population and have relatively large single-family houses with brightly colored plastic play equipment in fenced-in back yards. There need to be lots of big-box retail stores within easy driving distance, too.

That isn't a place every Minnesotan can afford or every Minnesotan who can will desire. It's just more likely a Republican will.

lee.schafer@startribune.com • 612-673-4302