Four things to keep an eye on as Pennsylvania's presidential election results come in

We've been writing for months about the strategies former President Donald Trump and Vice President Kamala Harris are pursuing to win Pennsylvania. If the polls prove true and this is the closest presidential election in history, there could be a bit of a shift here.

The gender difference could determine whether men or women vote more often. A movement of black and Latino voters toward or away from Democrats could be crucial.

But an easy way to think about the Pennsylvania race is to look at the margins in Philadelphia, its suburbs and the rest of the state.

How big of a lead does Harris have over Philadelphia?

The bigger Democrats can win in Philadelphia, the easier their path nationally will be. There's a reason Harris spent her last state visit with Oprah Winfrey and Lady Gaga on the steps of the Philadelphia Museum of Art.

From 1988 to 2012, Philadelphia gave Democratic presidential candidates an increasingly large buffer to offset Republican advantages in more rural parts of the state. In 1988, Democrat Michael Dukakis had a 210,000-vote lead in the city over Republican George H. W. Bush, who won the state and the presidency.

By 2012, the Democrats' lead in Philadelphia had grown to 492,000 votes, helping to secure the state for Democratic President Barack Obama. Trump managed to reduce that margin in the city in 2016 and again in 2020.

But Philadelphia still gave Joe Biden a lead of 471,000 votes, a far larger margin than Trump had in any other county.

Democrats in the city expressed confidence Tuesday about early voter turnout in the city, which stands at 7-1. Mayor Cherelle Parker predicted that Harris' vote total here could surpass Biden's in 2020. But the Trump campaign, which has paid more attention to the Democratic city than previous Republican presidential candidates, also saw positive signs in Pennsylvania. A Trump adviser said turnout was high in South Philadelphia and Northeast Philadelphia, two of the more Republican districts.

Can Trump get more out of rural Pennsylvania?

Trump's actions this year closely resembled the path he took in 2016 to boost support in rural and suburban parts of the state. The 61 counties outside Philadelphia, its suburbs and Allegheny have long been the main draw for Republicans, but Trump won a majority there.

Mitt Romney won a comfortable 396,000 vote margin in these districts in 2012. Trump more than doubled that lead, winning 816,000 votes in 2016 and becoming the first Republican to carry Pennsylvania since 1988. He managed to extend that lead by another 14,000 votes in 2020. Trump will almost certainly have to post big numbers again in rural Pennsylvania to bring the state back into Republican control this year.

He has focused most of his travel in the state on these areas, where the population is whiter and less college educated.

Can Harris extend the Democrats' lead in the Philadelphia suburbs?

A strong suburban result from Kamala Harris could be the key to Democratic victory. Biden's victory in 2020 was attributed in large part to the suburbs. He won it with 293,000 votes, an improvement of 105,000 votes over Hillary Clinton's margin in 2016.

Bill Clinton, historically a Republican stronghold, won a narrow lead in the four suburban counties in 1992, and that was the case Since then it's gotten bluer and bluer. In 2008, Obama achieved a vote advantage of over 200,000 in the suburbs. This margin fell in 2012 with Obama's successful re-election and then grew again in 2016 with Hillary Clinton.

Harris focused much of her travel on Philadelphia and its suburbs, where she sought to attract moderate Republican voters.

Will Trump's rural appeal be enough to offset Harris' strength in urban areas?

Overall, the question is whether Trump can expand his base beyond the Philadelphia and Pittsburgh areas. For Democrats, it's a question of whether the lead in Philadelphia, which is significant but narrowed slightly in 2020, will recover or grow.

And there's Allegheny County, where the Democrats' lead also improved enough for Biden to win Pennsylvania by about 80,000 votes in 2020. Both Trump and Harris held rallies in Pittsburgh on Monday, where the two candidates ran more than 100 times, Biden and friends, in search of the state's 19 electoral votes.