Former US first lady Barbara Bush has died aged 92.
Mrs Bush had reportedly been battling chronic obstructive pulmonary disease and congestive heart failure, and had been in and out of hospital.
The wife of former president George HW Bush, 93, and mother of ex-president George W Bush, 71, was being cared for at her home in Houston, Texas.
She died surrounded by her family after deciding not to return to hospital following a series of recent hospitalisations.
In a statement, the Bush family said: "A former First Lady of the United States of America and relentless proponent of family literacy, Barbara Pierce Bush passed away Tuesday, April 17, 2018, at the age of 92."
"She is survived by her husband of 73 years, President George H.W. Bush; five children and their spouses; 17 grandchildren; seven great grandchildren; and her brother Scott Pierce.
"She was preceded in death by her second child, Pauline Robinson ‘Robin’ Bush, and her siblings Martha Rafferty and James R. Piece."
Former president George W. Bush said: "My dear mother has passed on at age 92.
"Laura, Barbara, Jenna, and I are sad, but our souls are settled because we know hers was.
"Barbara Bush was a fabulous First Lady and a woman unlike any other who brought levity, love, and literacy to millions."
Among those to pay tribute to Mrs Bush were the Clintons, Hillary and former president Bill.
In a statement they said: "Barbara Bush was a remarkable woman. She had grit and grace, brains and beauty.
"She was fierce and feisty in support of her family and friends, her country and her causes.
"She showed us what an honest, vibrant, full life looks like. Hillary and I mourn her passing and bless her memory."
"We will never forget the courtesy and kindness she and President Bush showed us starting when I was governor in 1983. I'll always treasure my summer visits to Kennebunkport.
"Barbara joked that George and I spent so much time together I had become almost a member of the family, the ‘black sheep’ that had gone astray.
"Our hearts and prayers of out to President Bush; to George, Jeb, Neil, Marvin, Doro, and her grandchildren and great-grandchildren; and to the entire Bush family she loved so much.
"We know through them her remarkable strength, warmth and wit, and her devotion to our country will live on."
Mrs Bush is one of only two first ladies in US history who was also the mother of a president.
Abigail Adams, the wife of John Adams, a founding father of the nation and its second president, was the mother of John Quincy Adams, the sixth president.
During her tenure as the nation's first lady, Mrs Bush, the mother of six children, was a champion for global literacy and continued the work after she and her husband left the White House.
In January 2017, she and her husband were hospitalised at the same time.
She was being treated for bronchitis and the nation's 41st president was being treated for pneumonia.
The Bushes had been married for 73 years.
Mrs Bush was dubbed "The Silver Fox" by her husband and children.
She was known for her snow-white hair and for being fiercely protective of her family.
She was first lady when her husband was in the White House from 1989 to 1993.
Her son, Republican George Walker Bush, triumphed in the disputed 2000 U.S. election and was president from 2001 to 2009.
The father-and-son presidents were sometimes referred to as "Bush 41" and "Bush 43."
The Bushes had celebrated their 73rd wedding anniversary in January 2018.
Bush had an independent streak and could be sharp-tongued.
As first lady, she promoted literacy and reading but said she was more interested in running a household than in helping her husband run the country.
She discouraged speculation that she wielded political influence with the president like her predecessors - Ronald Reagan's wife, Nancy Reagan, and Jimmy Carter's wife, Rosalynn Carter.
"I don't fool around with his office and he doesn't fool around with my household," she once said.
"She'll speak her mind but only to him," said Jack Steel, a longtime Bush aide.
