(CNN – Keith Allen and Kate Andersen rower) — Rosalynn Carter, who as first lady worked tirelessly on behalf of mental health reform and professionalized the role of the president’s spouse, died Sunday at the age of 96, according to the Carter Center.

Rosalynn Carter passed away peacefully with family by her side at her home in Plains, Georgia, the center said in a statement.

“Rosalynn was my equal partner in everything I ever accomplished,” her husband, former President Jimmy Carter, said. “She gave me wise guidance and encouragement when I needed it. As long as Rosalynn was in the world, I always knew somebody loved and supported me.”

The Carter Center announced Friday that the former first lady had entered hospice care. She was diagnosed with dementia in May. Her husband began home hospice care in February, following a series of hospital stays.

Jimmy Carter was defeated in a landslide by Ronald Reagan four years after being elected. His single term in the White House included forging a rare peace agreement between Israel and Egypt that continues to this day, but it was also marked by soaring inflation and the Iran hostage crisis. Through it all, Rosalynn was by his side, and often whispering in his ear.

The Carters redefined and revolutionized the post-presidency and, through their joint efforts, they worked on world peace and human rights on behalf of the Carter Center, a nongovernmental Atlanta-based organization founded to “wage peace, fight disease and build hope.”

After leaving the White House, the couple traveled to hot spots around the world, including visits to Cuba, Sudan and North Korea, monitoring elections and working to eradicate Guinea worm disease and other neglected tropical diseases. Jimmy Carter won the Nobel Peace Prize in 2002.

“The Carter Center is a shared legacy. She’s been there digging latrines right next to him,” said the Carters’ friend Jill Stuckey, a leader at Maranatha Baptist Church, where both Carters attended and where Jimmy Carter taught Sunday school.

Rosalynn Carter’s most lasting individual legacy will be her efforts to diminish the stigma attached to people with mental illnesses and her fight for parity and access for mental health treatment. She also devoted her time to the Rosalynn Carter Institute for Caregiving at her alma mater, Georgia Southwestern State University, to help families and professional caregivers living with disabilities and illnesses.

In 1999, then-President Bill Clinton presented both Carters with the Presidential Medal of Freedom, the country’s highest civilian honor. He said they had “done more good things for more people in more places than any other couple on Earth.”

The ‘Steel Magnolia’

Rosalynn and Jimmy Carter shared what many would call a true American story and a genuine lifelong partnership.

In 2015, when the 39th president announced his brain cancer diagnosis, he was asked of which accomplishment he was proudest. He did not hesitate to say that it was marrying Rosalynn: “That’s the pinnacle of my life.”

He shared at another point the secret of his enduring marriage.

“Rosalynn has been the foundation for my entire enjoyment of life. … First of all, it’s best to choose the right woman, which I did. And secondly, we give each other space to do our own things,” he told Jake Tapper on CNN’s “The Lead” in July 2015.

It was likely that Eleanor Rosalynn Smith would cross paths with Jimmy Carter in their small hometown of Plains, Georgia. They grew up at a time when candy cost a nickel and everyone in town knew one another.

“Occasionally someone would open a restaurant, but it would never last very long,” Rosalynn wrote in her memoir, “First Lady from Plains.”

Rosalynn did not grow up with much money. Her mother was a dressmaker and her father was an automobile mechanic who died from cancer when she was 13. She helped raise her younger siblings and considered her father’s death the end of her childhood.

The Carters met through Jimmy’s sister, Ruth, who was Rosalynn’s closest friend. When Rosalynn saw a photo of Carter on Ruth’s bedroom wall she thought, “He was the most handsome man I’d ever seen.” She even asked Ruth if she could take his photograph home with her.

Both devout Southern Baptists, Jimmy and Rosalynn met after a church meeting and soon began dating. They were married not long after his graduation from the Naval Academy when she was 18 and he was 21.

“When we got married, I think I was kin to everybody that Jimmy wasn’t,” Rosalynn wrote in her memoir. “Once we got married, we were kin to everybody in town.”

As the wife of a naval officer, Rosalynn moved frequently and she managed a large household. The Carters had three children in quick succession: John William (“Jack”), the year after their wedding in Norfolk; James Earl (“Chip”) III, less than three years later in Hawaii; and Donnel Jeffrey (“Jeff”) in New London, Connecticut, in 1952. Their only daughter, Amy Lynn, was born in 1967, a year after Carter lost his first bid for Georgia governor.

Jimmy Carter had been accepted to an elite nuclear submarine program but resigned his commission in Schenectady, New York, after his father died so that they could return to Plains in 1953 to look after the family farm. He decided to relocate the family without asking Rosalynn’s opinion. Rosalynn was so furious that she refused to talk to him the entire drive south.

After that, Jimmy Carter said he consulted with his wife on all major decisions.

Later nicknamed the “Steel Magnolia” by the press – a reference she did not mind, saying once in an interview with C-SPAN that “steel is tough and magnolia is southern” –  Rosalynn was naturally shy and her knees would knock together when she had to give a speech in the early days of her husband’s political career in the 1960s.

But by the time he announced his presidential campaign in December 1974, she was a seasoned politician herself.

Describing her transformation from housewife to political partner, Carter aide Stuart Eizenstat said, “This shy woman blossomed in the most wonderful way.”

It was not long before she would number the president’s jokes so that he would not repeat any of them to the same group. She even started taking memory classes to remember faces and names and typed thank you letters to people her husband had met on the campaign trail. She stayed up until the early hours of the morning to work on her speeches.

First lady from Plains

Carter ran for president as a Washington outsider seeking to distance himself from the paranoia and cynicism of former President Richard Nixon. He had a group of Georgia volunteers, known as the “Peanut Brigade,” campaign for him.

Rosalynn hit the road with a vengeance, and when she arrived in a small town, she scoped out the tallest antennae and headed there – the local television and radio stations – to offer herself up for an interview. In her memoir, she wrote that some of the smaller stations with few employees had no idea who Jimmy Carter was.

Rosalynn came prepared, carrying a list of five or six questions she wanted asked. Nine times out of 10, she said, the station used the questions she suggested.

“I was getting my message across,” she said in her memoir.

For 18 months during the presidential campaign, she went to 105 communities in Iowa and spent 75 days in Florida in support of her husband.

“My nervousness began to disappear when I realized people seemed pleased to meet me, though I still had trouble with a dry throat and sometimes a trembling voice when I approached an interview or a speech,” she wrote in her memoir.

Carter won a narrow victory, capturing just 51% of the popular vote and 297 electoral votes to defeat President Gerald Ford, who had assumed the presidency upon Nixon’s resignation in 1974.

The Carters ignored security concerns and broke with tradition when they decided to walk hand-in-hand with their daughter Amy down Pennsylvania Avenue after the inauguration ceremony. It was part of their mutual desire to connect with people and move away from what they saw as Nixon’s imperial presidency.

Rosalynn even wore the same gold-embroidered sleeveless coat over a blue chiffon dress that she wore to her husband’s inauguration as governor in 1971 to the galas for his 1977 inauguration as president. It was designed by Mary Matise for Jimmae and she bought it from a store in Americus, Georgia.

As a young girl, she had admired then-first lady Eleanor Roosevelt, an influential global leader who took on issues such as civil rights and poverty. Once in the White House, Rosalynn helped to transform the office of first lady and became the first to hire a chief of staff whose government salary and rank were equal to the president’s chief of staff.

She was the first first lady to work out of the East Wing. Before her, first ladies worked from an office on the second or third floors of the White House in the family’s private residence. And under her watch, full-time positions in the East Wing grew by almost 20%. But her ambitious approach to the role drew criticism, particularly her controversial decision to sit in on her husband’s Cabinet meetings.

As first lady she fought for the passage of the Equal Rights Amendment, which would have amended the Constitution to outlaw civil rights discrimination based on sex.

Steven Hochman, who has worked with the Carters since 1981 and is director of research at the Carter Center, said Rosalynn did not hesitate to disagree with her husband in public as the years went on. During speeches, the former president liked to tell audience members that one of his elementary school teachers used to tell her students that “any child could be president.”

“Mrs. Carter would correct him,” Hochman recalled in an interview. “She’d say, ‘No, she never said that. She said, any boy could be president.’”

In her memoir, Rosalynn recalled eating lunch with her husband in the Oval Office every Wednesday, similar to the vice president’s weekly lunch with the president. The ritual came about because Rosalynn had pressing topics to discuss, including their personal finances, their children and the issues she deeply cared about, including mental health.

Before those weekly lunches, when the president stepped off the elevator on the second floor at the end of the day, she would approach him with an onslaught of questions and suggestions. She talked to mothers about how high fuel prices were affecting their family budgets and she met with children in struggling schools, and she wanted to bring these issues to his attention.

Once he suggested a weekly lunch, she began to organize such conversations, putting important notes in a brown leather folder. The folder sat on her desk in her bedroom and she stuck notes in it throughout the week. By the time she brought it with her to their Wednesday lunch, it was packed.

Mental health crusade

Rosalynn Carter’s signature issue was mental health. When she was campaigning for her husband during his 1970 race for governor, she was overwhelmed by the number of people who asked her what she would do for a relative dealing with mental illness.

“One day, when Jimmy was speaking at a rally, I got in line with everybody else to shake hands with him,” she recalled decades later in an interview with the Carter Center. “He saw who I was, grinned, and asked, ‘What are you doing here?’ ‘I came to see what you are going to do about mental health when you are governor,’ I replied.”

She had a distant cousin with mental illness and she remembered running and hiding when she would hear him coming down the streets of their small town singing loudly. “He probably wanted nothing more than friendship and recognition, yet he was different, and when I heard him, my impulse was to flee,” the former first lady wrote in her memoir.

The experience left such a deep impression on her that she devoted much of her time in the White House to advocating for better care for people with mental illnesses. As Georgia’s first lady, she helped shift treatment to community mental health centers, and in the White House, she helped her husband create a Presidential Commission on Mental Health.

The day the commission was announced, Rosalynn Carter told the press that she had just gotten a note informing her that the Department of Justice prohibited the president from appointing a close relative, such as a wife, to a civilian position. Up until then, she had been planning to chair the committee.

“There is, however, no problem with you being designated as honorary chairperson,” she said, amid laughter from reporters. “So I’m going to be a very active honorary chairperson.”

In 1979, she became the second first lady to testify before Congress (Eleanor Roosevelt was the first) when she spoke about the need for mental health reform.

As first lady, she tried to be in the family’s private quarters to greet 9-year-old daughter Amy by 4 p.m. on school days, and at 6:30 p.m. they had dinner together most nights. Amy was the first presidential child to attend a public school since Theodore Roosevelt’s son.

‘I am much more political than Jimmy’

In the White House, Rosalynn would urge her husband to put off controversial decisions until after his reelection. She freely admitted, “I am much more political than Jimmy and was more concerned about popularity and winning reelection.”

She lobbied to have her husband fire Secretary of Health, Education and Welfare Joe Califano. According to longtime Carter family friend and White House aide Jerry Rafshoon, she was angry at Califano over an anti-smoking campaign, fearing that it would hurt Carter’s standing in tobacco-producing North Carolina.

“I wanted Jimmy to fire Joe Califano long before he ever did,” she wrote in her memoir, “and my reasons were purely political.”

She opposed Carter’s Rose Garden strategy not to campaign against his 1980 Democratic primary challenger, Massachusetts Sen. Ted Kennedy, and instead to stay holed up in the White House negotiating the release of American hostages in Iran.

She also did not agree with Carter’s decision to bar alcohol from White House social events, though they did ultimately serve wine and spiked punch. The impression of out-of-touch Southern Baptists in the White House created a “stereotype that we never lived down,” she said.

She was sent to Central and South America to deliver a serious message on human rights. At first, leaders and the press were skeptical about a first lady taking such an important political trip, but eventually they realized that she had a direct line to the president.

She brought home tangible achievements: Ecuador pledged to sign and ratify the American Convention on Human Rights; the military leader of Peru vowed to give up power (four years later Rosalynn attended the inauguration of the democratically elected president of Peru); and the president of Colombia pressed to move negotiations forward on the Panama Canal.

Rafshoon recalled that it was Rosalynn’s idea to hold the Middle East peace talks at Camp David, which became her husband’s greatest achievement as president. She wanted the negotiation to happen there because of Camp David’s tranquil and isolated location in the Maryland mountains. At the 13-day Camp David summit, Rosalynn took almost 200 typed pages of notes. But any accomplishments of the Carter presidency were ultimately overshadowed by a 444-day hostage crisis in Iran, in which revolutionary students stormed the US Embassy in Tehran and took more than 60 Americans hostage.

The brunt of campaigning in 1980 fell to Rosalynn as Jimmy Carter decided to stay in the White House to handle the crisis. She checked in several times a day from the campaign trail, and when she could not speak with her husband, she talked with Carter’s national security adviser, the late Zbigniew Brzezinski, who discussed how to handle the crisis. “I kept her abreast because I knew she would be discussing those issues with the president,” Brzezinski said in an interview.

Her biggest regret in life was her husband losing reelection in 1980.

“I’d like people to know that we were right, that what Jimmy Carter was doing was best for our country, and that people made a mistake by not voting for him,” she said in her memoir.

The Carter Center

Rosalynn and Jimmy Carter had four children, 12 grandchildren and several great-grandchildren. When the Carters left the White House in 1981, they returned to Plains and embarked on the longest and most ambitious post-presidency in American history.

With the exception of Harry and Bess Truman, the Carters are the only post-World War II president and first lady to return to their hometown and, since their return, Rosalynn worked to revitalize the working-class community, revamping the local inn and adding a butterfly garden.

She and her husband were active members of the Maranatha Baptist Church, where she served as a deacon. But they are perhaps most famous for their humanitarian work with the Carter Center, to which they devoted 51 weeks a year (the remaining week they spent working for Habitat for Humanity).

In a 2016 interview, Rosalynn reflected on the nearly four decades that had passed since leaving Washington.

“I missed having Jimmy in the Oval Office taking care of our country,” she said. “I have never felt as safe as I did when he was there. I still have a bully pulpit to work on issues I like, and because he was president, I have unlimited opportunities. It is a good life.”