Rosalynn Carter, former first lady of the United States, dead at 96

• Rosalynn Carter has died at 96, the Carter Center reported.
• The former first lady long advocated for people with mental illness.
• Her 77-year marriage to Jimmy Carter was the longest marriage of any presidential couple ever.

Rosalynn Carter, the former first lady of the United States, died Sunday at 96.

After a brief period in hospice, announced on November 17, Carter died at home surrounded by friends, family, and her husband, former President Jimmy Carter.

Earlier this year, the Carter Center announced that Carter had been diagnosed with dementia.

Rosalynn Carter had a decadeslong romance with her husband, Jimmy Carter

Carter lived a long and successful life alongside her husband, whom she knew almost her entire life.

She first met Jimmy Carter when she was a baby, and they married in 1946 in their hometown of Plains, Georgia.

They were married for 77 years, the longest marriage of any presidential couple.

"The best thing I ever did was marrying Rosalynn," Jimmy Carter said in a 2015 interview with The Carter Center. "That's the pinnacle of my life."

She helped him run his businesses and political campaigns and advocated for people with mental illness

Carter was instrumental to her husband's success in both business and politics — he frequently turned to her for advice.

When Jimmy Carter was first elected governor of Georgia, Rosalynn Carter turned her focus to helping people in the state with mental-health issues on the Governor's Commission to Improve Services to the Mentally and Emotionally Handicapped.

Later, when Jimmy Carter announced his candidacy for president, he said his wife was "much more political" than him, while the White House website credits her for helping her husband through her strong belief in his abilities.

As first lady, she again focused on mental-health advocacy. As the honorary chair of the President's Commission on Mental Health, she oversaw a group dedicated to enacting policy change for people with mental illness.

After leaving the White House, she continued her philanthropic work with her husband

After Jimmy Carter lost his reelection bid, he and Rosalynn returned to Georgia and founded The Carter Center in Atlanta in 1982.

The Carter Center has since monitored elections for democracy worldwide and almost entirely wiped out the Guinea-worm disease.

In the mid-1980s, the couple began collaborating with Habitat for Humanity, where they worked to build and repair more than 4,300 homes with the group.

Despite her political responsibilities, she remained focused on her family. She has four children and 22 grandchildren with Jimmy Carter.

Jimmy Carter, now 99 and the longest-lived US president, has been in hospice care since February. He's been enjoying peanut-butter ice cream and has said he's "at ease with death."

The couple's grandson, Jason Carter, said in a recent interview that his grandparents have enjoyed spending their "last chapter" together at home, celebrating their longevity, their family, and their love in the same tiny Georgia town they both were born in.

"That word love is really the one that defines certainly their personal relationship, but also the way they approach this world," Jason Carter, now the chair of The Carter Center's governing board, said.

The Associated Press contributed to this report.