A new poll in Louisiana shows Donald Trump leading by 20 points. And the reason is no surprise: white voters.

What is surprising, though, is the degree to which that statement is true — i.e. just how much Trump dominates among whites. Hillary Clinton takes just 12 percent of them in the Mason-Dixon poll; Trump takes 75 percent.

A late-September Quinnipiac University poll in Georgia showed something similar there, with just 16 percent of white voters backing Clinton and 74 percent backing Trump.

In both polls, Democrats completely dominated among black voters, as they regularly do. So the end result was that almost all black voters were going for Clinton and the vast majority of white voters going for Trump.

This is not a new phenomenon, it should be emphasized. But it is notable that racial-political polarization in the South, and especially the Deep South, appears to be sticking around even with the nation's first black president no longer on the ballot.

In 2012, white voters in the Deep South (defined here as five states: Louisiana, Mississippi, Alabama, Georgia and South Carolina) favored Mitt Romney 77 to 22. In 2008, it was even more lopsided — 78 to 20 in favor of Sen. John McCain (R-Ariz.). As Nate Cohn put it back in 2014, “the Democrats have become the party of African Americans and . . . the Republicans are the party of whites.”

These polls and others suggests that gap is going to be similar in 2016 — if not bigger in a state or two. A Washington Post-Survey Monkey online poll of all 50 states last month showed white voters favoring Donald Trump by a 71-to-22 margin in these five Deep South states — on a par with the 2012 margin.

That racial polarization is not nearly so big across the rest of the country. Exit polls in 2012 showed Romney winning white voters by much smaller margins elsewhere: 6 points in the Northeast, 5 points in the West and 16 points in the Midwest. McCain in 2008 actually lost white voters to Barack Obama in the Northeast and West. And today, those regions remain much more competitive in Trump vs. Clinton, within margins of 10 points or less in the Survey Monkey poll.

But in the Deep South — and, to a lesser extent, in the South more broadly — things look about as bad as ever for white Democrats.

The Louisiana and Georgia polls described above are the most lopsided gaps we've seen. An Atlanta Journal-Constitution poll of Georgia last week, for instance, showed Clinton taking 20 percent of the white vote. And the one public poll we have of Mississippi — also from Mason-Dixon, but from March — had Clinton pulling 20 percent of the white vote there. But again, these are only on a par with Obama's numbers.

The question going forward is whether this is a response to Trump's explicit appeals to working-class white voters (who tend to be more dominant in the South) or whether this is the new normal going forward — whether the candidates include an Obama or a Trump. Are we in for an electoral future in the Deep South in which basically all African Americans vote for Democrats and nearly all white voters vote for Republicans?

Perhaps recognizing that prospect, Vice President Biden has been making the case that Democrats can't give up on appealing to the white, working-class voters who are going strongly for Trump, even as they are a shrinking portion of the electoral pie. His argument has more to do with winning Congress in areas like his birthplace of Scranton, Penn., but it's an even more acute problem in the South, where Democrats were picking off House seats as recently as a decade ago but have started coming up empty. (There are precisely zero white Democrats representing the Deep South in Congress, after the last two lost in 2014.)

“[Trump's] appeal to their anger, their concern, their fears about the changes taking place in the country and the world, are not illegitimate,” Biden told The Washington Post's Paul Kane last week. “I mean, this is one of those great transition periods in world history.”

And in the near term, for the first time in a long time, this gap actually matters when it comes to the presidential elections results. One of these Deep South states, after all, is suddenly polling like a competitive race: Georgia. The newest Fix Forecast has it at “lean Republican,” with recent polls showing Trump up between 2 and 4 points.

Those recent polls show Clinton taking between 16 percent and 24 percent of the white vote, the latter according to a Marist College poll. If she wants to actually win, she'll need it to be close to the latter, if not higher. She may score that in some areas of the country. But it's tough to meet that mark in today's Deep South.