GEOFF BENNETT: Tomorrow night's presidential debate between Donald Trump and Kamala Harris will take place in Philadelphia in a state that could prove to be the deciding factor in the race for the White House.

Lisa Desjardins takes us inside one Pennsylvania county with a track record of picking the winner, a place both parties think could signal how the state and possibly the country could vote.

LISA DESJARDINS: Drive down a gravel road just past a cornfield and you will find how Vice President Harris plans to win the election.

VANESSA BOULETTE, Harris Organizer: If someone says they are concerned about reproductive health care, you want to talk about Kamala Harris' opinions on that.

LISA DESJARDINS: In swing Northampton county, Pennsylvania, Democratic volunteers meet weekly to strategize, before hitting the streets and pushing every way they can for Harris.

VANESSA BOULETTE: Hello, my name is Vanessa and I'm a volunteer for the Harris campaign.

There's a lot of enthusiasm for since Kamala Harris got into the race for getting out and voting for her.

But I think people are very concerned.

It's such a close race.

MAN: Help people get involved, lord, and help people work to save America.

LISA DESJARDINS: Several miles away in the in Northampton County, Republicans too are gathering for voter outreach.

In one room, we see the span of the MAGA coalition, some focused on Trump as a strong leader, at least two others on conspiracies.

Among the things this woman told us is that Joe Biden is dead, replaced by a fake.

For Rodney Nace, it is about Trump's track record.

He voted for Barack Obama once, but is now all in on Donald Trump.

RODNEY NACE, Trump Supporter: He's very, very outspoken.

I could be, too, if I get wound up.

But he gets the job done.

And when he gets the job done, it was always for the betterment of the country.

LISA DESJARDINS: Of the 3,000 counties in the country, just 25 of them voted for the winner in the last four elections.

Of the tiny handful in swing states, Northampton County was the closest in 2020.

They voted for Joe Biden by less than one point.

Lifelong resident Carlos Diaz grew up with the lights of the Bethlehem steel plant.

CARLOS DIAZ, Pennsylvania Resident: Every night, blue flames would shoot out of that.

And you would hear the clanging and banging and it was always like chh, chh, chh, that never stopped.

LISA DESJARDINS: That was your childhood all the time.

CARLOS DIAZ: That was the soundtrack to my childhood for sure.

LISA DESJARDINS: That was in the '80s, but, within years, the plant shut down, snuffing out thousands of jobs that were the town's economic lifeline.

Did those jobs ever come back?

CARLOS DIAZ: No.

They shifted a portion to Maryland, but the majority were lost and gone for good.

LISA DESJARDINS: Carlos is a truck driver and a lifelong Democrat voting for Harris.

Like her, he opposes abortion bans and as a father of a child with autism.

He was appalled at attacks on V.P.

nominee Tim Walz's son, who has a non-verbal learning disorder.

Perhaps most of all, Carlos sees the working class at stake.

CARLOS DIAZ: These people who are not part of the 1 percent, who are not corporations, why they would think its in their economic self-interest to vote Republican is beyond me.

I cannot comprehend that.

Joe Biden went to a union picket line.

How amazing was that, a sitting president on a union picket line?

That just made my heart swell.

LISA DESJARDINS: Northampton has an industrial draw.

It is a key corridor between major East Coast cities.

But it is also a compact version of the whole state, with urban areas like Bethlehem, lush rural farms, and middle-class suburbs, like in Easton, where Jackie Crowell today is watching her grandson.

A retired schoolteacher, she is centered on family and her faith.

JACKIE CROWELL, Pennsylvania Resident: I am voting for Donald Trump.

It's policy over personality for me.

I'm a conservative Christian.

And he aligns, the party aligns much more with my ideals as a Christian, as the Democratic Party.

LISA DESJARDINS: She is Republican and anti-abortion and applauds Trump for his role in overturning Roe v. The matriarch of a family of wrestlers, she opposes transgender women playing women's sports.

JACKIE CROWELL: Oh, there's my great-grandparents.

LISA DESJARDINS: These are wonderful.

Jackie's politics are also rooted in family, immigrant grandparents from Germany and Italy, once Democrats.

JACKIE CROWELL: My grandmother used to say when I was a little girl, Democrats are for the poor., Republicans are for the rich.

If she were alive today, she would be Republican, no question about it, because the Democrat Party of her day is not the Democrat Party today.

LISA DESJARDINS: Jackie blames Democrats and Harris for high prices, from food to homes, and what she sees as a lower work ethic.

JACKIE CROWELL: I'm very work hard, don't expect the government to take care of you.

Do what you have to do for your family.

Doesn't mean you're going to be millionaires, but you will have a comfortable living if you work hard.

LISA DESJARDINS: That idea unifies this swing county, hard work.

But the divide is everywhere, like at the popular Fegley's Brew pub.

At the bar, a veteran for Trump is struggling in this economy.

JIMMY PEARCE, Trump Supporter: I haven't been able to finance a House because the rates are too high.

LISA DESJARDINS: A few feet away, a group of hard no's on Trump see a threat to rights and democracy.

LYDIA REMINSKY, Harris Supporter: I generally just do not think that Mr. Trump could lead the country at all.

LISA DESJARDINS: One thing we noticed, we did not find any Democrats for Trump.

But we did meet Republicans against him.

What don't you like about Trump?

DOLORES COLE, Republican Voter: Where do I start?

LISA DESJARDINS: Like Dolores Cole.

We met her at that Republican event.

She's been in the party 62 years and does not mince words about Trump, noting he is a convicted felon, or about Trump voters.

DOLORES COLE: They just worship their God, who is Trump.

And that's it.

He can do no wrong even though he does.

So they don't think for themselves.

I am thinking for myself and for my country.

LISA DESJARDINS: Love for country is evident here, along with strong divide over what that means.

Like so much else in Northampton county, who wins here likely will come down to one thing, who works the hardest.

For the "PBS News Hour," I'm Lisa Desjardins in Northampton County, Pennsylvania.