When Cardinal Robert Prevost was just a first grader, one of his neighbors predicted that he would eventually become the first American pope, according to his brother’s statement to ABC News.

On Thursday, that prophecy came true, when Prevost was elected to be the 267th pontiff, the first from the United States.

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Before he was Pope Leo XIV, the 69-year-old pontiff grew up the youngest of three brothers in the south suburb of Dolton.

He always wanted to be a priest, his middle brother, John Prevost, told ABC News in New Lenox Thursday.

“He knew right away. I don’t think he’s ever questioned it. I don’t think he’s ever thought of anything else,” John Prevost said.

As a child, Pope Leo XIV “played priest,” John Prevost said. “The ironing board was the altar.”

As the conclave approached, Pope Leo had begun to gain recognition as a top candidate for the papal seat, explained Rev. James Martin, who contributes papal insights to ABC News.

On Tuesday, prior to the cardinals entering their confidential conclave, John Prevost conversed with his brother, expressing his belief that he could indeed become the first American pope. However, Pope Leo dismissed the idea, remarking, “‘They’re not going to choose an American pope,'” as shared by his brother.

“He just didn’t believe it, or didn’t want to believe it,” John Prevost said.

He said he would be ready, if that was God’s wish.

As the new pope, John Prevost said he expects his brother will follow in the late Pope Francis’ footsteps as a voice for the disenfranchised and poor.

“I think they were two of a kind,” John Prevost said. “I think because they both were in South America at the same time — in Peru and in Argentina — they had the same experiences in working with missions and working with the downtrodden. So I think that’s the experience that they’re both coming from.”

On Thursday, John Prevost’s phone has not stopped ringing, with friends, family and journalists, calling from around the world.

He said he learned that his brother had become the pontiff at the same time as the rest of the world.

“Even when it was announced, and I’m sitting there watching him speaking, this isn’t real. I’m going to wake up in a minute because it’s just, my niece was on the phone with me, and she’s just screaming and screaming. She’s calling work, or she’s not going in today. It’s just unreal,” Prevost said.

It was in August of last year, while visiting his brother in New Lenox that then-Cardinal Robert Prevost presided over Mass at St. Jude Catholic Church in New Lenox.

He met personally with a number of parishioners, including the parents of ABC7 Chicago cameraman Stephen Bourque.

“I was so excited. I jumped up and started screaming, and my dogs were going crazy because they didn’t know why I was screaming. And I was like, I actually met this man. I shook the hand of the new pope,” parishioner Peggy Bourque said.

“To know that he becomes the pope of this entire world, it’s just absolutely fantastic. Sorry, I get emotional because it to me is a true blessing from God,” Stephen Bourque said.

During that Mass last year, then-Cardinal Prevost spoke of the need to be charitable, and of service.

It was perhaps a preview of what will likely be his central message as pope.

His oldest brother, Louis Prevost, told Sarasota ABC affiliate WWSB that he was “half expecting it, half not,” adding, “I still was in shock.” Louis Prevost said he was feeling under the weather and lying in bed at the time the big moment came.

“My wife called and said, ‘white smoke, white smoke,'” Louis Prevost told WWSB. “So I turned the TV on, watched the white smoke. It took almost an hour till (the elected pope emerged from St. Peter’s Basilica) and when the cardinal came out, and we’re all waiting, and he goes, and he mentioned Roberto, I knew right away.”

South suburban residents proud of pope with local ties

Some Catholics in the south suburbs showed their pride Thursday.

Some visited a vacant church that was part of the pope’s childhood.

There was a sense of true pride stretching across the south suburbs, as dozens of people came out to the landmark of St. Mary of Assumption church.

They took photos of the place where Pope Leo XIV began his rise to the Vatican, as they said it’s surprising to know that the pope hails from the south suburbs.

“It’s a happy day for Chicagoland, a happy day for the Archdiocese of Chicago,” Riverdale resident Jimmy Berschinski said.

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Chicago-area residents have been overwhelmed with excitement, as they realize the ties that connect them to the new pope.

“We were just floored; we didn’t think an American pope would ever happen. And now, here we are. He’s from the South Side, and that’s where we’re from. It’s just very exciting,” Evergreen Park resident Jim Connolly said.

St. Mary of Assumption church has been a vacant landmark since 1993, but, back in the late 1950s and throughout the 1960s, it was home to the Prevost family.

“I would come here, help sweeping classrooms, cleaning classrooms after school and stuff like that. And I know the Prevost family. They were wonderful people, and it’s just amazing, amazing,” Berschinski said.

Berschinski said he went to school with Pope Leo’s brothers at Mendel Catholic High School, where the pope’s mother was also a librarian.

He said Thursday marked a moment of pride for him and many other South Siders, embracing the new head of the Catholic Church.

“I wanted to come by and relive the memories; this is absolutely amazing. The Prevost family, they have to be so proud,” Berschinski said.

Others continued to rush by the church Thursday, as the doors remained open, allowing people to walk through the hallways where Pope Leo began his rise to the Vatican.

“I couldn’t wait to get here, and now I went inside. It is beautiful, and I hope they will renovate it soon,” Chicago resident Mary Simons said.

That sentiment was shared by many, who hope the church can be rebuilt and maybe even welcome Pope Leo back.

“If he wants to say a Mass here they better do something; there’s a big hole in the roof,” Berschinski said.

“I’m kind of amazed it’s still here. Maybe they’ll refurbish church and get it back open; that’d be fantastic,” Connolly said.

Noelle Neis says she was a year behind then-Robert Prevost at St. Mary’s in Dolton. She and her siblings knew him in school, and their families sat together during Mass.

“I’m like, ‘oh my gosh.’ Then all my siblings called. It was amazing; I was shaking, very exciting,” Neis said. “He wasn’t in some fancy house or some fancy country; he was just one of us.”

Neis has followed his career.

“We’ve kind of always followed him, ever since he became bishop with the Augustians, and the cardinal, and that he was part of it. Nobody expected it; it was like never an American pope,” Neis said.

Neis, who continues to be a practicing Catholic, is looking forward to what Pope Leo will do.

“I hope he is a pope for the people, and all people. I hope he is more understanding of people in the world today,” Neis said.

Although St. Mary’s closed years ago, Neis says this might motivate classmates to have a school reunion and invite Pope Leo.

ABC News’ Alex Perez and Meredith Deliso contributed to this report.