GEOFF BENNETT: In a recent report, Judy Woodruff explored the history of violence in Northern Ireland as a warning to our own country about how quickly identity-based conflicts can spiral out of control.

Tonight, she returns to Belfast with a look at efforts to bridge the deep divisions that remain there decades after that conflict officially ended.

It's part of her ongoing series, America at a Crossroads.

JUDY WOODRUFF: Opening early each morning on Belfast's Lanark Way, this peace gate, a symbol of ongoing separation between Catholic and Protestant neighborhoods, allowing easy passage between the Shankill Road, representing Protestant loyalty to Britain, and the Falls Road, representing Catholic Republicans and their long fight for independence.

The summer months are cool, but tense in Northern Ireland, when Protestants march through Belfast on Saturdays.

In mid-July, they light huge bonfires to mark long-ago British victories over the Irish, antagonizing their Catholic Republican neighbors.

In August, Catholics take their turn, marking the Feast of the Assumption and the internment of prisoners without trial during the Troubles.

ALAN WAITE, Founder, R City: There was a two-day running gun battle with the Republicans... JUDY WOODRUFF: Running gun battle.

ALAN WAITE: ... in West Belfast and the British army.

JUDY WOODRUFF: Right around here, right where we are?

ALAN WAITE: Right around -- right where we are.

JUDY WOODRUFF: Alan Waite grew up during the Troubles in Highfield Estate, a working-class Protestant neighborhood in West Belfast.

ALAN WAITE: We still live in a divided community.

And we're still.. JUDY WOODRUFF: It's still as divided as it was?

ALAN WAITE: Just not as divided, but in terms of where we live and in terms of how we go to school and spend our time, it's still very much you do your stuff on your side of the wall and we will do ours on the other side of the wall.

JUDY WOODRUFF: Pierce McConnell grew up on the other side of that wall.

PIERCE MCCONNELL, Program Manager, R City: So, it defines a lot in terms of a young person's upbringing, their culture, what they believe in.

JUDY WOODRUFF: Born in 1997, a year before the Good Friday Agreement, he was raised in the Ardoyne, a mostly Catholic working-class neighborhood less than two miles from Highfield.

PIERCE MCCONNELL: You're constantly told, do not go there, do not engage with those people, do not do this.

So then automatically you're curious, but you're also -- there's a bit of a fear.

JUDY WOODRUFF: Twenty-seven years after the signing of the Good Friday Agreement, the political accord that mainly ended the violence, many neighborhoods, communities and the vast majority of schools here in Northern Ireland remain divided by identity.

But a number of groups are working across that divide to try to maintain the peace and build a more integrated future.

More than a decade ago, Alan Waite founded R City to integrate young people from single-identity neighborhoods like Highfield and Ardoyne.

As early as age 12, they begin building friendships across the divide at its community center, traveling to the beach for summer camp.

MAN: We like to take the young people out of their community, out of their surrounding environment.

JUDY WOODRUFF: And even overseas to places like South Africa, where they learn about conflicts beyond their own borders.

Alan Waite says it's about trying to break the generational cycle here.

ALAN WAITE: Unfortunately, when you're brought up, you're brought up in a community, you're brought up in a family who's maybe staunch and pass a lot of their values and a lot of their beliefs to the younger generation below them.

And, therefore, if you're only hearing the stories that's around you, then you're getting the same thoughts and feelings that those older generation had many years ago.

PADRAIG GREEN, Member, R City: My grandfather was really forceful on, don't go into areas.

They're bad people.

JUDY WOODRUFF: Padraig Green is 17 years old and grew up in the Ardoyne, the Catholic enclave.

He joined R City when he was 13 and says through friends he's learned about the Protestant traditions he once feared.

PADRAIG GREEN: So I got to learn more about their culture, but also not only that.

I also got to learn that they are actually just human, they're just like us.

They live more or less the same life, like same houses, same families, stuff like that there.

DARCY MONTGOMERY, Member, R City: People my age care about Catholics and Protestants, but they weren't allowed to witness what actually properly happened.

JUDY WOODRUFF: Seventeen-year-old Darcy Montgomery grew up in Highfield, the Protestant neighborhood.

Through R City, she's become friends with more Catholics, but she says change is slow here.

DARCY MONTGOMERY: These peace walls, they shouldn't still be up.

Why would they need to be up?

But then, if you try to take them down, there would be fighting.

So there needs to be a problem with the fighting going on and with the conflict between the two communities.

JUDY WOODRUFF: Pierce McConnell is now the program manager at R City, but was also part of its inaugural class.

He says they're trying to build the shared space that society still hasn't, where, over many years, young people can build relationships stronger than the divisions of the past.

PIERCE MCCONNELL: If you look at every relationship, positive relationship you have in your life, it probably came through having something with longevity in it.

So your friends come through your job that you have maybe been in a long time, your school that you went to, your university, a sport you played, a hobby you had.

You need that time spent together.

You need to build those relationships and build that understanding.

MONICA MCWILLIAMS, Co-Founder, Northern Ireland Women's Coalition: Most importantly, they're speaking to each other for other sides, where, in my day, I never had that opportunity.

JUDY WOODRUFF: Monica McWilliams was 14 when the Troubles in Northern Ireland broke out.

MONICA MCWILLIAMS: This is also the first day of the peace talks.

JUDY WOODRUFF: She was 44 when she signed the Good Friday Agreement after co-founding the Northern Ireland Women's Coalition and being elected to the multiparty negotiations.

A trailblazer for women's rights, she has since worked around the world on peace-building efforts and says grassroots efforts like R City are a key feature.

MONICA MCWILLIAMS: Politicians think, we were elected, so we're the only people who can speak as representatives.

Uh-uh.

The people on the ground are participating every single day as much as you are in politics.

It might be small-P politics, but every single thing they're doing is political.

And that's my message to those who are losing faith in other parts, particularly in the States.

They say, what difference can we make?

If you get together, if you're a collective, if you get organized, information, education, agitation, and it works.

But do not disparage the politicians either, because you have to be in the system to change the system.

JOE KENNEDY, Former Special Envoy to Northern Ireland: They have recognized that you can't ask people to compromise completely on who they are.

JUDY WOODRUFF: Former Democratic Congressman Joe Kennedy served as special envoy to Northern Ireland under the Biden administration, and he says there's another lesson for Americans about identity and politics.

JOE KENNEDY: A Protestant shouldn't tell a Catholic in Northern Ireland they can't be Catholic.

A Catholic can't tell a Protestant, you can't be Protestant.

A nationalist can't tell a unionist not to stay true to their loyalties and vice versa.

Those are ingrained traits as to the identities of who those folks are.

Yet they have found a way to try to build a community on top of that, recognizing that an essential way for peaceful coexistence to make sure that my kid has a healthy and safe and vibrant future is to make sure that your child does as well.

ALAN WAITE: The main thing for us is that we build a relationship so strong that, when it comes to talking about hot topics, more importantly is our relationship, rather than the topic, whether it be the color of the flag on top of the city hall, or maybe an Irish language speaking act.

Look, we can have debates about that, but what's more important is what we have got, what me and you have as friends.

JUDY WOODRUFF: Today, older generations marvel at how much progress society has made since the Troubles, when they grew up.

For young people like Padraig Green and Darcy Montgomery, there's so much more to be done.

Twenty years from now, what do you want Northern Ireland to be like?

DARCY MONTGOMERY: I would like there to be more mixed schools, so Protestant and Catholic schools learning the same thing.

PADRAIG GREEN: I would love there to be no peace gates, no peace walls, just a completely integrated community, like, nationwide.

JUDY WOODRUFF: But back on Lanark Way, each evening, the peace gate, painted to commemorate the 25th anniversary of the Good Friday Agreement, closes again, until tomorrow.

For the "PBS News Hour," I'm Judy Woodruff in Belfast, Northern Ireland.