Carter had been in hospice care since mid-February 2023 at his home in Plains, Georgia -- the same small town where he was born and once ran a peanut farm before becoming governor of the Peach State and running for the White House.

Carter died "peacefully" at his home in Plains, "surrounded by his family," the Carter Center said in a statement.

"My father was a hero, not only to me but to everyone who believes in peace, human rights and unselfish love," Chip Carter said in the statement.

Carter was the longest-lived US president -- an outcome that seemed unlikely back in 2015 when the Southern Democrat revealed he had brain cancer.

But the US Navy veteran and fervent Christian repeatedly defied the odds to enjoy a long and fruitful post-presidency, after four years in the Oval Office often seen as disappointing.

During his single term, Carter placed a commitment on human rights and social justice, enjoying a strong first two years that included brokering a peace deal between Israel and Egypt dubbed the Camp David Accords. 

But his administration hit numerous snags -- the most serious being the taking of US hostages in Iran and the disastrous failed attempt to rescue the 52 captive Americans in 1980. He also came in for criticism for his handling of an oil crisis.

In November of that year, Republican challenger Ronald Reagan clobbered Carter at the polls, relegating the Democrat to just one term. Reagan, a former actor and governor of California, swept into office on a wave of staunch conservatism.

Active post-presidency 

As the years passed, a more nuanced image of Carter emerged -- one that took into account his significant post-presidential activities.

He founded the Carter Center in 1982 to pursue his vision of world diplomacy, and he was the recipient of the 2002 Nobel Peace Prize for his tireless efforts to promote social and economic justice.

He observed numerous elections around the world and emerged as a prominent international mediator, tackling global problems from North Korea to Bosnia.

Carter, known for his toothy smile, said basic Christian tenets such as justice and love served as the bedrock of his presidency. He taught Sunday school at Maranatha Baptist, his church in Plains, well into his 90s.

Outside the White House, where the flag was lowered to half-staff, tourist Yoni Neirman remembered Carter as a leader "who tried to do good things for this country and for people."

"I think he was a real statesman, and that kind of person doesn't seem to exist, at least not in the near future," the Vermont resident said of the first president she had ever voted for.

In Georgia, retiree Dorner Carmichael expressed the same sentiment.

"Every time you lose a person of such integrity, who spent his life in service, you just wonder who will fill his shoes," the 75-year-old told AFP.

'Leader, statesman and humanitarian' 

As condolences came in, many focused on Carter's character, with President Joe Biden, in televised remarks, saying he "lived a life measured not by words, but by his deeds."

"The rest of the world looks to us... and he was worth looking to."

White House leaders past and future joined Biden in issuing remembrances, with Bill Clinton saying in a statement that Carter "worked tirelessly for a better, fairer world." 

George W. Bush said Carter's legacy would "inspire Americans for generations," while Barack Obama said the former leader "taught all of us what it means to live a life of grace, dignity, justice, and service."

Donald Trump said Americans owed the Democrat "a debt of gratitude," later adding, in a second social media post, that "I strongly disagreed with him philosophically and politically."

One of Carter's defining foreign policy achievements -- negotiating the return of the Panama Canal to Panama -- has come back into focus as Trump has threatened to retake the channel.

Egyptian leader Abdel Fattah al-Sisi on Sunday hailed Carter as "a symbol of humanitarian efforts" for his role in brokering the 1978 Camp David Accords, predicting his work would "remain etched in the annals of history."

Carter was preceded in death by Rosalynn, his wife of 77 years. She died on November 19, 2023 at age 96. 

The former president, who looked frail, poignantly appeared at her memorial service in a wheelchair, with a blanket on his lap bearing their likenesses.

Carter is survived by the couple's four children, three sons and a daughter.