She was fiercely protective of him throughout his Hollywood career, eight years in the White House, an assassination attempt and the Alzheimer’s disease that marked his later years.
Ronald Reagan died in 2004.
Nancy Reagan became an advocate for discovering a cure for Alzheimer’s, the progressive brain disorder that destroys memory. She had already fronted the high-profile “Just Say No” anti-drug campaign during her husband’s time in the White House.
In their tribute, US President Barack Obama, a Democrat, and First Lady Michelle Obama said Nancy Reagan redefined the role of first lady.
“Nancy Reagan once wrote that nothing could prepare you for living in the White House,” the Obamas wrote in a joint statement on Sunday.
“She was right, of course. But we had a head start, because we were fortunate to benefit from her proud example, and her warm and generous advice.”
The Obamas also praised her work in fighting Alzheimer’s disease as did fellow former first lady and current Democrat White House hopeful Hillary Clinton.
Republicans vying to replace Obama in the 2016 US presidential election have also been paying tribute.
As Nancy Davis, she was a Hollywood actress when she married Ronald Reagan, a prominent film actor, in 1952.
They had two children together – Patti Davis, an actress, and Ron Jr., who pursued careers in ballet and television.
Ronald Reagan had divorced another actress, Jane Wyman, in 1948. They had a daughter, Maureen, and adopted a son, Michael.
Michael was among those paying tribute after Nancy’s death, taking to Twitter to say: “She is once again with the man she loved.”
Nancy served as first lady of California during her husband’s stint as California governor from 1967 to 1975 before he became president after a decisive victory over incumbent Democrat Jimmy Carter in 1980.
She was diminutive and publicly soft spoken but her strong will, high-tone tastes and clout with her husband made her a controversial figure during his presidency.
As Reagan’s wife, political partner and adviser, she became one of America’s most potent first ladies, alongside the likes of Franklin Roosevelt’s wife, Eleanor, Woodrow Wilson’s wife, Edith, and Bill Clinton’s wife, Hillary.
“I see the first lady as another means to keep a president from becoming isolated,” she said in 1985. “I talk to people. They tell me things. And if something is about to become a problem, I’m not above calling a staff person and asking about it. I’m a woman who loves her husband and I make no apologies for looking out for his personal and political welfare.”
Tiny and frail in her later years, Reagan devoted her time to caring for her ailing husband at their home in Los Angeles’ exclusive Bel Air enclave.
She was always a stickler for protocol and detail and stoically presided over the former president’s weeklong funeral and celebration of his life in June 2004.
One of her most trying times as first lady came when John Hinckley stepped out of a crowd outside a Washington hotel on March 30, 1981, and fired six shots toward the president, striking him in the chest. A .22-caliber bullet punctured his lung and nearly entered his heart.
“Honey, I forgot to duck,” he told her at the hospital.
Some critics lambasted Nancy Reagan as a meddlesome “dragon lady,” derided her anti-drug campaign and ridiculed her for consulting an astrologer to schedule presidential events.
President Reagan called this view of his wife “despicable fiction,” saying in 1987: “The idea that she is involved in governmental decisions and so forth and all of this, and being a kind of dragon lady – there is nothing to that.”
The reputation was established during Reagan’s time as California governor and followed her to Washington. She was first accused of being a vacuous spendthrift interested chiefly in renovating and buying new china for the White House, lavish entertaining, her designer wardrobe and the like, then portrayed as a cunning manipulator of policy and people.
Advocates of the latter view saw her influence as virtually unlimited in such matters as the dumping of presidential advisers, efforts to get a nuclear arms accord with the Soviet Union and her husband’s decision to seek a second term in 1984.
Mrs. Reagan had her left breast surgically removed in October 1987 after a cancerous tumour was discovered.
The cause of her death was congestive heart failure, according to a spokeswoman for the Ronald Reagan Presidential Library in Simi Valley, California.
Nancy Reagan will be laid to rest there, next to her husband.