The numbers, announced Saturday morning, show that Biden will eke out a win in Pennsylvania by at least a 0.5% margin, not far from the 0.7% that marked Donald Trump’s victory four years ago. Indeed, the story in the Keystone State encapsulates the scenario in most of the battlegrounds: How, in a game of inches, Biden did just a bit better than Hillary Clinton with seniors and rallied a gigantic turnout in the blue-leaning suburbs that narrowly blunted a never-before-witnessed working-class surge for Trump.

“This wasn’t a big shift or a wave,” says Chris Borick, the Muhlenberg College professor who oversees its Institute of Public Opinion voter surveys. “About the same percentage of voters in Philadelphia voted for Biden, but a lot more of them turned out. In the rural parts of the state that are deep red, Trump did even better than in 2016. It was small shifts on the margin that made the difference.”

Borick notes that only two of Pennsylvania’s 67 counties changed colors. In both, the swings were small. But those subtle trends were also bellwethers of a narrow Biden win. “Those two were the first to report on Wednesday,” says Borick, giving an early hint that the former Vice President would win by a hair. In Rust Belt icon Erie County, Trump flipped the state Republican four years ago, winning 48.6% to 47%. But the ultimate coal mine canary is Northampton County, home to Bethlehem in the central-eastern tier. Obama carried the county easily on his two runs, but Trump shocked the pollsters in winning by three points in 2016. This time, Biden rewrote the plot once again, notching what is at least a 0.5% win.

“The great thing about Northampton is that it has a little of everything,” says Borick. “It has deep industrial roots as the birthplace of Bethlehem Steel and an urban core in Bethlehem. It also has lots of Hispanic voters and major suburbs because of its proximity to New York and location 20 minutes from Philly.” For Borick as a veteran pollster, Northampton represents something of a microcosm of Pennsylvania—and the nation as a whole. “When I saw the shift from the early returns in 2016, it was a tell that Trump could win,” says Borick. The slight shift to Biden on Wednesday, he adds, telegraphed that the former Vice President had the upper hand.

Nothing epitomized Trump’s 2016 more vividly than his gains in another industrial stalwart, Lackawanna County, whose hub is Scranton. Trump got 47% of the vote in the former Democratic stronghold, improving on Mitt Romney’s numbers by 12 points. But Biden staged a big blue comeback, winning by 8.5%. “That’s the county where Biden spent the first 10 years of his life and had his campaign headquarters. It’s right near the state line with Delaware,” says Borick. “That he beat Clinton’s totals by several points was another great predictor.”

The trends in Erie, Northampton, and Lackawanna, says Borick, showed that Biden was making modest progress where Trump had notched huge gains four years earlier. In fact, the whole election wasn’t about the wild swings of 2016 but gentle moves at the margin. He says that Trump lost support from seniors because of what many of the 65-and-over crowd viewed as his bungled response to the COVID-19 pandemic. But once again, Borick doesn’t think the swing was a big one. What sealed Biden’s victory was the battle between the state’s two paramount blocks, which were each fiercely passionate about their candidate: rural voters in farming and fracking regions and their blue-leaning, opposite numbers in the metros, notably Pittsburgh and Philadelphia, and their suburbs.

In 2016, Clinton swept 82.5% of the ballots in Philadelphia County. This time, Biden dipped a tad to 80.8%. He made up for the shortfall in Pittsburgh’s Allegheny County, hitting 59.3% to Clinton’s 56.6%. In the rest of the state, Trump logged 55% of votes, beating his 2016 margin overall, with an especially big lift in the oil-rich western areas. “Biden’s comments on ending fracking probably helped Trump somewhat in those areas. But that support was mainly baked in,” says Borick. “Once again, the shift was modest—the story of the whole election in Pennsylvania.”

It was the one big shift that handed Biden his narrow win––the jump in turnout across the entire state. By late afternoon on Nov. 6, Lackawanna, Philadelphia, and three surrounding counties, Delaware, Chester, and Montgomery, had already cast 1.642 million ballots for Biden. That’s 142,000 or almost 10% more than in 2016. And Philadelphia and Lackawanna have some ballots still outstanding, mail-in votes predicted to break heavily for Biden. Trump also generated huge turnout in the rest of the state, especially in the farming and fracking regions. But although he got 70%-plus in those areas, he also slipped versus 2016 in populous areas such as Lackawanna and Northampton.

So overall, Biden managed a slightly bigger turnout in blue strongholds, where his share of the votes matches Clinton’s, than what Trump amassed in the red areas he dominates. That tiny edge made the difference. It was a fascinating interplay of currents and crosscurrents that decided the outcome. And none of them were big enough to produce anything like a wave.