April 13, 2021

Why Pennsylvania is the most important state on the map right now

  • Joe Biden and President Donald Trump each spent time campaigning in Pennsylvania in September.
  • In 85% of simulations where Biden wins the presidency, he also wins the state of Pennsylvania, according to Decision Desk HQ’s Director of Data Science and Race Call Team, Scott Tranter.
  • Before swinging for Trump in 2016, Pennsylvania had not voted for a Republican since President George H.W. Bush in 1988.
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Following Joe Biden’s four-stop train tour of Pennsylvania last week and recent stops from President Donald Trump in September, it’s become evidently clear that the commonwealth is among the highest priorities for both candidates.

According to election simulations from Decision Desk HQ, winning Pennsylvania is imperative for both candidates.

In DDHQ simulations, instances where Biden wins the presidency are accompanied by a victory in Pennsylvania 85% of the time. Conversely, Trump wins a second term 70% of the time when he is simulated a win in Pennsylvania.

Election forecasting models work by determining a state of the race based on polling and other input data, and then by randomly simulating the outcome of the election a certain number of times.

According to DDHQ Director of Data Science and Race Call Team, Scott Tranter, if Biden loses Pennsylvania in November, his pathway to the Oval Office becomes much more difficult. Of all the simulations that yielded a Biden win, he won without the commonwealth’s support just 15% of the time. 

Among political scientists, Pennsylvania had been known as a “blue wall state,” or a state which historically votes Democrat in presidential elections. Trump previously emerged victorious by winning over upper Midwest blue wall states Michigan, Pennsylvania, and Wisconsin. 

In the 2016 presidential election, the commonwealth’s voters sided with Trump over Hillary Clinton by just 0.7 percentage points, according to Ballotpedia. Before swinging for Trump, Pennsylvania had not voted for a Republican president since President George H.W. Bush in 1988. 

Biden grew up in Scranton, Pa. and he’s hoping his home state advantage will boost him over Trump in November. Among states that flipped from Democrat to Republican in 2016, Pennsylvania has the second most electoral votes, 20, behind only Florida with 29. 

Even without winning Pennsylvania, Tranter said, Biden “can still win by bringing Wisconsin, Michigan, and Florida back into the Democratic column.”

If Trump is to lose in Pennsylvania and Wisconsin, he can still emerge victorious in November if he can replicate the rest of his 2016 electorate map. If he loses in both Pennsylvania and Florida, he’ll face an uphill battle as he will need to rely on wins in states like Colorado or Virginia where he is currently behind in the polls by over ten points.

“In our simulations, some of the most common victory maps for Trump in which he loses Pennsylvania are simply his 2016 map, but with Pennsylvania and either Michigan or Wisconsin defecting to Biden,” Tranter said.

Forecasting from DDHQ shows Biden with a 75.5% chance of winning Pennsylvania. Recent polling from Siena College and the New York Times from September 25 to 27 has Biden leading Trump by 9% among likely voters in the commonwealth.