If you’ve been around these parts for any period of time, you’re familiar with my theory of community tipping points. Basically, it’s my belief that most communities are relatively split in their support between the two major parties. In an election, a 60-40 split is an enormous blowout, but it’s not particularly uncomfortable to be part of a minority of 40 percent. However, when the split gets closer to 3 to 1, there can be social costs to holding minority political beliefs. This is when people begin to hide their opinions or even to change them to prevent suffering consequences for themselves or their children. This is choice made by Republicans in our cities all the time, and it’s a choice Democrats in rural areas made in 2016. It’s how a county can go from giving Obama 40 percent of the vote to giving Clinton less than 25 percent.

As Katie Glueck explains in the New York Times, that’s swinging back now. See if any of the following sounds familiar to you:

As a divisive presidential campaign enters the final stretch, there is evidence that some Democrats deep in Trump country — the kind of voters who avoided political discussions with their neighbors, tried to ignore Facebook debates and in some cases, sat out the last election — suddenly aren’t feeling so shy. It’s a surge in enthusiasm that reflects the urgency of the election for Democrats desperate to oust President Trump, one that could have significant implications for turnout in closely fought battleground states that the president won in 2016.

No one expects Westmoreland County, which includes Latrobe and Scottdale, to flip to Democratic control after Mr. Trump won it by more than 30 percentage points in 2016. And no one doubts the passion of the president’s supporters in counties like this across Pennsylvania and the Industrial Midwest. Pennsylvania in particular is home to some longtime Democrats who have aligned themselves firmly with Mr. Trump in recent years.

The question is whether Biden-backing Democrats in counties like Westmoreland are engaged enough this year to prevent Mr. Trump from recreating his overwhelming 2016 margins of victory in white working-class areas, the kind of support that compensated for his losses in cities and suburbs elsewhere last time. If Mr. Biden can reduce Mr. Trump’s support in these regions while producing even bigger numbers in the suburbs and cities than Mrs. Clinton did in 2016, Mr. Trump’s path becomes all the more difficult.

“Even if we just cut the margin,” Mr. Biden said on his recent train tour through eastern Ohio and western Pennsylvania, “it makes a gigantic difference.”

That’s the dynamic I described in my 2017 cover piece for the Washington Monthly on how to win rural voters without losing liberal values. It’s important to get these communities back in the 60-40 range where Democrats feel like accepted members of the community rather than moral lepers whose children will go uninvited to their classmates’ birthday parties. As Biden says, cutting the margin in these communities will make a gigantic difference, and that’s partly because avoiding the tipping point also avoids the compounding effect that goes along with it.

Even though Trump’s Pennsylvania voters are incredibly committed to their candidate, there are still a lot of Trump defectors.

A Monmouth poll of registered voters in Pennsylvania last week showed that Mr. Trump’s lead among white voters without a college degree had fallen from 22 points in early September to just nine points this month, suggesting that Mr. Biden was cutting into a demographic that is crucial to the president’s hopes of winning re-election. Multiple recent polls have found Mr. Trump’s standing with those voters down compared with his 2016 result in Pennsylvania.

It turns out that the so-called deplorables weren’t complete irredeemable. And now there are enough Biden supporters popping up in these communities that they can find and lend support to each other. They don’t feel like they need to go underground, and they’re not being dissuaded from voting at all.

To his credit, Biden is fighting for these votes, but his success so far is due less to the Democrats following my advice over the last four years than in Trump’s performance in office, including his handling of the coronavirus. Whatever works, I suppose, but there’s no doubt will do worse this time in the suburbs, so his only path to victory in Pennsylvania is do even better in rural areas than he did in 2016. It just doesn’t look like that’s going to happen.