Former US First Lady Rosalynn Carter, the wife of ex-President Jimmy Carter, has died at the age of 96.
The Carter Center confirmed in a statement that she died peacefully with her family by her side.
On Friday, it was reported that she had entered a hospice care home in the state of Georgia, and was spending time with her 99-year-old husband, who has been in hospice care since February.
Mrs Carter was diagnosed with dementia in May.
"Rosalynn was my equal partner in everything I ever accomplished," said Mr Carter in the statement.
"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."
Mrs Carter was born Eleanor Rosalynn Smith on 18 August 1927.
She married Jimmy Carter on 7 July 1946 and they had four children.
The Carters' son, Chip, described her as a loving mother, extraordinary first lady and "a great humanitarian in her own right."
"She will be sorely missed not only by our family but by the many people who have better mental health care and access to resources for caregiving today."
She is also survived by 11 grandchildren and 14 great-grandchildren, after losing a grandson in 2015.
When her husband began his political career in the 1960s - first as Georgia state senator, governor, and later US president - Mrs Carter was focused on raising mental health awareness and reducing the stigma attached to people with mental illnesses.
As first lady of Georgia she was a member of a governor's commission to improve services for the mentally ill, and as US First Lady she became honorary chair of the President's Commission on Mental Health, which was key to the passage of a 1980 act that helped fund local mental health centres.
After leaving Washington she and her husband founded the Carter Center in 1982, through which she continued her advocacy work for mental health, early childhood immunisation, and other humanitarian causes.
The couple were also key figures in the Habitat For Humanity charity, helping build homes for families in need.
They received recognition for their humanitarian work in 2002 when Mr Carter was awarded the Nobel Peace Prize.
In a 2013 interview with US TV network C-SPAN, she said: "I hope our legacy continues, more than just as first lady, because the Carter Center has been an integral part of our lives.
"And our motto is waging peace, fighting disease and building hope. And I hope that I have contributed something to mental health issues and help improve a little bit the lives of people living with mental illnesses."
US President Joe Biden paid tribute to Mrs Carter, saying she "walked her own path, inspiring a nation and the world along the way".
"On behalf a grateful nation, we send our love to the entire Carter family and the countless people whose lives are better, fuller, and brighter because of Rosalynn Carter," President Biden posted on X, formerly Twitter.
Former First Lady Michelle Obama said: "When our family was in the White House, every so often, Rosalynn would join me for lunch, offering a few words of advice and always - always - a helping hand.
"She reminded me to make the role of First Lady my own, just like she did. I'll always remain grateful for her support and her generosity."
Former President George W Bush and former First Lady Laura Bush said Mrs Carter was "a woman of dignity and strength".
In a statement, they said: There was no greater advocate of President Carter, and their partnership set a wonderful example of loyalty and fidelity.
"She leaves behind an important legacy in her work to destigmatize mental health."