The mythology of Jimmy Carter begins and ends in Plains, the small Georgia town that raised him and kept drawing him back.

Yet roughly 150 miles away is Atlanta, a city just as essential to understanding the life of the 39th president. If Plains was his home, Georgia’s capital was his stage. If Plains reflected Mr. Carter’s small-town character, Atlanta fit his global ambitions.

While it was never a permanent home, Atlanta allowed him to develop policy priorities and kick off a national political career. Then, after leaving Washington, it gave him the space to burnish a humanitarian legacy, housing his efforts to promote equality, peace and democratic ideals.

Now, because Mr. Carter and his wife, Rosalynn, chose to place the Carter Center, their presidential library and the crown jewel of their post-presidential work, in the city, it is where hundreds of visitors will shuffle through the cold to pay their respects while he lies in repose through Tuesday.

“It would have been inconceivable to put everything in Atlanta and to move to Atlanta, because that’s not where they’re from, that’s not who they are,” Jason Carter, Mr. Carter’s grandson, said in an interview. But, he added, “the platform that was available to them in Atlanta was going to be exactly what they needed to have this global jumping-off point.”

Mr. Carter was undeniably shaped by the years he spent in youth on his father’s peanut farm. But beginning with his campaign to serve in the State Senate, he sought to bridge what was often a yawning divide between the rural region where he grew up and the urban engine of the state.

The effort helped shape a career that played out equally on large public stages like Atlanta and more intimate and personal ones like Plains.

“He could relate to people who did not have voices in those big rooms,” said Shannon Heath-Longino, who recounted how Mr. Carter listened to Eva Davis, her grandmother and a champion for revitalizing the East Lake neighborhood of Atlanta, about her vision. He even went to Washington with her to help secure crucial housing funds, she said.

“We had not had the best relationship with political leaders and people being people of their word once they’re elected,” she added. “He was just a man of his word.”

There are the obvious personal influences of the big city. The younger Mr. Carter joked that his grandfather may never have had a Pepsi, given the Coca-Cola headquarters in Atlanta, and always tried to take his commercial flights through Delta Air Lines, in a nod to its prominence in the city.

And there was his rain-or-shine devotion to the Atlanta Braves. Mr. Carter and his wife often attended games and were on occasion caught on the kiss cam that panned over the home crowd.

“He would sit there in the rain and cheer the team on — and he was a die-hard fan, a real fan,” said Terry McGuirk, the chairman of the Braves. He added that Mr. Carter had perhaps “the purest love of the game that I have ever seen out of a president.”

But as a political figure who grew his influence in Atlanta, he helped shape its growth and many of the people who would go on to lead or represent the city and the ideals it valued.

As a state senator, Mr. Carter voted to establish the city’s main public transportation authority and later, as governor, oversaw a sales tax increase to help fund its growth and operations. He overhauled the state government, oversaw new mental health and education policies and established a judicial nominating commission.

He “diversified government,” said Dr. Meredith Evans, the director of the president’s library and museum, by elevating women and people of color into positions of power.

“His door was always open — and people sought his counsel in Atlanta,” she added, calling it “a quiet force.”

Mr. Carter was also instrumental in preserving the legacies of some of Atlanta’s most important figures, including Dr. Martin Luther King Jr. He hung a portrait of the civil rights icon in the Capitol gallery during his term as governor. As president, he designated Dr. King’s home and neighborhood a national historic site and helped raise millions of dollars to help fulfill the King family’s ambitions of building the King Center.

“He laid that foundation to make that recognition,” recalled Dr. Bernice King, the daughter of Dr. King and chief executive of the King Center. She added, “these partners, relationships, working together have really made Atlanta a world class city — I don’t think it could have happened without the alignment of the King family and President Carter.”

After his single term in the White House, it quickly became clear that Mr. Carter, who was 56 at the time, would return to his home state.

“He wasn’t the kind of person who’s going to move into a mansion in Atlanta and tap into corporate boards,” said Sheffield Hale, the president and chief executive of the Atlanta History Center. But, Mr. Hale added, “he was deeply rooted in Georgia.”

His devotion to Plains and frugal inclinations meant he spent years sleeping on a pullout couch or Murphy bed during his regular visits to Atlanta. But he still honed connections with Emory University, where he would serve on faculty, team up with the school to open the Carter Center and frequently lecture. (Mr. Carter earned tenure after 37 years, at 94.)

He also helmed the Atlanta Project, a plan to address housing, unemployment and other problems in the city, ahead of the 1996 Olympics.

“Being a relatively young man when he left the presidency and determined, as he was, to make the most of the gifts he’d been given and the opportunities he’d been given, Plains was not going to be a big enough of a landscape for President Carter and his ambitions,” said Joe Crespino, an Emory University history professor. He added that his students frequently peppered the former president with questions based on his papers.

The placement of the Carter Center — which houses a traditional presidential library in tandem with a private organization focused on health care and peace — cemented the former president’s connection to Atlanta. (Dr. Evans, of the Carter library, noted that the easy logistics of the city helped overtake Mr. Carter’s initial vision to put the library in Plains.)

Its permanent location was not without conflict, as the initial plans for the center included building a new highway — decades after Mr. Carter, as governor, had opposed similar construction. A coalition of neighborhoods fought against the new parkway until a compromise was struck, one that led to both the creation of the center and about 200 acres of greenery for what is now Freedom Park.

In a symbol of its importance, the center is now the centerpiece of the tributes to Mr. Carter in Georgia, with flowers and jars of peanuts left at its entrance. The family made a point of holding its first full service there in Atlanta on Saturday, before mourners arrived to pay respects.

“He was a great neighbor, a tremendous friend,” said Brian Maloof, who still owns Manuel’s Tavern, the Atlanta bar where Mr. Carter announced his campaign for governor and continued to visit over the years. “We’re going to miss him.”