With less than two months until Election Day, Pennsylvania has emerged as the keystone state in each party’s plan to win the White House.

The Pennsylvania focus is so great that the firm AdImpact, which tracks political advertising purchasing, reports that both the Donald Trump and Kamala Harris campaigns are spending more money on political advertising in Pennsylvania than in any other swing state this cycle.

Kamala Harris flew to Pittsburgh on Sept. 5 and remained in the state through the Sept. 10 presidential debate – which took place in, you guessed it, Pennsylvania.

The “Keystone State” – known as that since the 1800s due to Pennsylvania’s geographic, economic and political importance – has received a lot of love this election cycle. Both candidates appear to be treating Pennsylvania as their second home until Election Day.

I am an assistant professor of political science at Gettysburg College in Pennsylvania, where I research and teach courses on American politics, public opinion and statistical methods.

Why is Pennsylvania so pivotal for both campaigns?

In 2020, Pennsylvania was decided for Democrat Joe Biden by about 1.16 percentage points, which translates to 80,555 votes.

That’s a small margin, but it was not even among the top three closest states that cycle. Wisconsin, Arizona and Georgia were all decided by even smaller margins. North Carolina, Nevada and Michigan were also very close, though not quite as close as Pennsylvania.

Six out of the seven states most likely to decide the 2024 election were won by Biden in 2020. Trump carried North Carolina.

So why........

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