Nancy Reagan, the wife of former US president Ronald Reagan, has died at the age of 94.
Mrs Reagan, who had been living in Bel Air, Los Angeles, died of congestive heart failure, the Ronald Reagan Presidential Library said.
Her 52-year marriage was once described as the US presidency's greatest love affair.
From 1981-89, she was one of the most influential first ladies in US history.
She was initially criticised for an expensive renovation of the White House, but later become a much-loved figure.
She will be buried next to her husband, at the Ronald Reagan Presidential Library in Simi Valley, California, the library said in a statement.
Like her husband, Mrs Reagan was a former Hollywood performer who made it all the way to the White House.
As Nancy Davis, she was an actress during the 1940s and 1950s and married Reagan, a prominent film actor, in 1952.
She served as first lady of California during her husband's stint as California governor from 1967 to 1975 before moving into the White House after his decisive victory over Democratic president Jimmy Carter in 1980.
As first lady, she sought to emulate the style of one of her predecessors, Jackie Kennedy.
To this end, she extensively redecorated the White House, accepted designer dresses worth $US1 million and a 4732-piece set of china worth $US209,000.
But this spending spree provoked a huge outcry from people outraged by what they saw as profligacy and waste while millions of Americans were losing their jobs.
Public opinion was also swayed by accusations that Mrs Reagan had a frosty personality, often consulted astrologers, and ordered the dismissal of White House chief of staff Donald Regan in 1987.
"I see the first lady as another means to keep a president from becoming isolated," she once said.
"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," Mrs Reagan said.
President Barack Obama and his wife, Michelle Obama, have offered condolences, saying Mrs Reagan "redefined the role" of first lady and became a strong advocate for Alzheimer's research.
In a joint statement, the Obamas said: "Nancy Reagan once wrote that nothing could prepare you for living in the White House."
They said she was right about that, but thanks to her, they had a head start, benefiting from her example and her warm and generous advice.