Well...it's complicated. Despite all the stories that have focused--almost obsessively--on college educated voters in the Philly suburbs (where indeed Biden made significant gains), a detailed analysis of the election results reveals just how many moving parts there were to Biden's victory. Biden competed well all across the state and built a victory from many small vote contributions, even as he held down Trump's margins in areas where the incumbent needed to overperform. This is clearly laid out in Nick Field's lengthy post on Decision Desk HQ where he looks at 2016-2020 trend down to the precinct level in key parts of the state.
"[T]he simplest and most obvious observation from looking at the data is that Joe Biden’s win was pieced together from small widespread gains which allowed him to consistently chip away at Trump’s 2016 advantage.
According to Biden Campaign Manager Jen O’Malley-Dillon, this outcome was no accident. In a post-election podcast interview with Obama campaign vet David Plouffe, she described their game plan.
“We weren’t willing to just do the things that people would typically do. Just go to Philly, just go to Pittsburgh. We knew we had to increase our margins in these other counties,” O’Malley-Dillon explained. “You always want to go super-deep in areas but we also had to go incredibly wide across the whole state in order to come up with the margins.”...
Back in 2016, I noted that the shifts in Lackawanna and Luzerne Counties from Obama to Clinton were enough to swing the state to Trump all on their own. As a result, Scranton native Joe Biden made this portion of PA a major priority.
The candidate made several stops here in the summer and fall, with a heavy focus on his hometown. First of all, Biden unveiled his ‘Build Back Better’ economic recovery plan in Scranton. Later on, it was the site of a CNN Town Hall that served as an early example of the drive-in format the campaign frequently employed. It was also at this event where Biden first introduced his final major slogan, categorizing the race as “between Scranton and Park Avenue”. Finally, he began Election Day with a visit to his childhood home.
All that attention paid off on November 3rd as Biden scored three point improvements in both Lackawanna and Luzerne. Likewise, he made up ground in other neighboring spots. Among these areas was Monroe, home to the tourist-friendly Pocono Mountains, as well as ruby-red counties like Pike and Montour. This suggests that Biden’s focus on the Scranton TV market paid serious dividends.
You may not realize just how populous [the south central] region of Pennsylvania is, or just how fundamental it is to Republican candidates. After all, Trump scored his largest surplus of votes in Lancaster and York Counties.
Accordingly, this area is a prime contender for O’Malley-Dillon’s theory that margin control was critical for Biden’s candidacy. For instance, the suburbs around each county seat allowed the Democratic nominee to secure a swing of about four points in both Lancaster and York. As a result, Donald Trump emerged with about 4,000 less net votes there compared to 2016....
In the run-up to Election Day, Lt. Governor John Fetterman was fond of telling anyone who would listen that whoever won Erie would win PA, and thus the White House. He proved to be prescient, as the state’s sole lakeside county was one of two to flip from Trump to Biden....
After the glimpse we got in Philadelphia, the Lehigh Valley provides a fuller view of Biden’s under-performance with Hispanics. Allentown, Reading and Bethlehem each have Latino-heavy districts where Biden struggled to match Clinton’s totals. His strength in the suburbs, however, allowed him to overcome these deficits both here and throughout the country.
Additionally this sector of the state is home to Northampton, the other Trump/Biden county. The Democratic nominee turned a 3.8% defeat here in 2016 into a narrow 0.7% win. Meanwhile he scored an even larger victory in Lehigh (4.7% to 7.6%), while trimming the shortfall in Berks (9.9% to 8.1%). ...
This was the corner of the state that powered Trump’s rise in 2016, and racking up even more massive margins here was critical to his re-election strategy. After all it was in Butler on Halloween where he proclaimed “We win Pennsylvania, we win it all — you know that, right?”
So was Trump able to improve his performance in Southwest PA? Yes…and no.
In contrast to the eastern half of the state, where Biden posted small yet significant boosts, Trump was able to continue to run up the score in the Southwest. This was especially apparent in Greene and Fayette counties, which lie on the West Virginia border, where the incumbent benefitted from notable surges in support.
The key difference from 2016, though, was in the counties which surround Allegheny. Beaver, Butler, Washington and Westmoreland all swung a few points towards Joe Biden, driven by voters in the towns along the Ohio and Monongahela Rivers. "
The lesson here: It takes competing in a whole state and among all types of voters to rebuild a wall. Don't let anyone tell you different.