(CNN) A big question heading into this cycle was whether Democrats' best path to winning back the White House ran through the Sun Belt or the Great Lakes (i.e. Rust Belt). While we won't know for certain which pathway was best for them until the votes are actually counted, the current data shows a pretty clear divide.
If former Vice President Joe Biden is to win this election, his best chance probably runs through the Great Lakes.
Two new polls out Sunday morning are demonstrative of a larger trend. Biden was up 51% to 46% in a CBS News/YouGov poll in Wisconsin. CBS News/YouGov also found Biden at 50% to President Donald Trump's 47% in Arizona, a result well within the margin of error.
These polls taken in isolation wouldn't be that noteworthy, but they speak to the larger aggregate.
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Hillary Clinton won contests containing 232 electoral votes. Were Biden to hold the Clinton states (and polls indicate that he probably will), he needs to find an extra 38 electoral votes.
Those extra 38 electoral votes are likely to come from the six closest states Trump won in 2016: Arizona (11 electoral votes), Florida (29 electoral votes), Michigan (16 electoral votes), North Carolina (15 electoral votes), Pennsylvania (20 electoral votes) and Wisconsin (10 electoral votes). You can also add in the one electoral vote from Nebraska's Second Congressional District, which Trump won by just 2 points in 2016.
(Nebraska, like Maine, gives an electoral vote to the winner of each congressional district.)
Now, look at the polling aggregates in each of those contests.
What you see here is a pretty clear divide between the Great Lake and Sun Belt states. Biden has advantages of 7 points to 8 points in the Great Lakes, while his leads are 3 to 4 points in the Sun Belt. Nebraska's Second District is really not part of either region, though it is part of the Midwest (where the Great Lakes is mostly situated) and lacks the racial diversity of the Sun Belt states.
The key in these poll numbers is that Biden doesn't actually need Arizona, Florida or North Carolina to win. Just by winning in Michigan, Wisconsin, Pennsylvania and holding the Clinton states, Biden gets to 278 electoral votes.
Obviously, that map doesn't leave Biden a lot of room for error, but it is good enough.
Not surprisingly, statistical models suggest that Pennsylvania is the state most likely to determine the Electoral College winner in 2020.
An examination of the demographic voting patterns in the last few cycles and national polls indicate that Biden's relative strength in the Great Lakes makes a lot of sense.
Remember that Michigan, Pennsylvania and Wisconsin formed part of what was deemed "the blue wall" heading into the 2016 election. All three states had voted Democratic in every presidential election since 1992.
Trump was able to break through that blue wall because of his strength among White voters without a college degree. These voters make up about 50% or more of the voters in Michigan, Pennsylvania and Wisconsin. They make up a significantly lower percentage in the Sun Belt, which is more racially diverse.
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The live interview national polls taken since the first debate have Trump winning White voters without a college degree by about 17 points nationally. That may seem like a big lead, but Trump led among that group by 30 points in the final pre-election polls in 2016.
Trump's declining support among White voters without a college degree is bigger than his declining support overall and has been consistent throughout this cycle. Meanwhile, Biden's been at best matching and usually underperforming Clinton among Black and Hispanic voters, who are a far bigger factor in the Sun Belt than Great Lakes.
Additionally, Biden's been doing about 10 points better among White voters overall and nearly 20 points better among White women than Clinton did. All of these trends manifest more greatly in the Great Lakes than Sun Belt.
Importantly, you'll note that the comparison here controls for the Great Lake poll misses in 2016. We're focusing on the national polls, which were largely accurate in 2016. Also, we're doing an apples-to-apples comparison between pre-election polls then and now.
And if you still don't believe the polls, just look at the results in 2018 and the actions of the Biden campaign. House Democrats did significantly better in Michigan, Pennsylvania and Wisconsin than in Arizona, Florida and North Carolina. They also won the governorship and Senate races in Michigan, Pennsylvania and Wisconsin in 2018.
There's a reason why Biden based his campaign in Philadelphia and has been outspending Trump by factors of greater than 2:1 in Michigan, Pennsylvania and Wisconsin.
For Trump to win, he'll probably need to knock down the big blue wall again. If he can't, Biden's probably the next president.