© FILE This Jan. 20, 1981 file photo shows former President Reagan as he gives a thumbs up to the crowd while his wife, former first lady Nancy Reagan, waves from a limousine during the inaugural parade in Washington following Reagan's swearing in as the 40th president of the United States. Nancy Reagan made the red power suit her signature as first lady. (AP Photo/FILE)

Former first lady Nancy Reagan passed away Sunday of congestive heart failure at the age of 94, the Reagan library announced.

She will be buried next to her husband, former President Ronald Reagan, at his presidential library in Simi Valley, Calif.

"Prior to the funeral service, there will be an opportunity for members of the public to pay their respects at the Library," its statement said. "Details will be announced shortly."

Tributes began pouring in to the former first lady who played a key role in her husband's political career and presidency.

"With the passing of Nancy Reagan, we say a final goodbye to the days of Ronald Reagan," said Mitt Romney, the Republican presidential nominee in 2012. "With charm, grace, and a passion for America, this couple reminded us of the greatness and the endurance of the American experiment."

Long-time aide Michael Deaver once said that, “without Nancy, there would have been no Governor Reagan, no President Reagan."

Born Anne Frances Robbins on July 6, 1921 -- and given the name Nancy by her mother -- Mrs. Reagan's father left the family when she was young. Her mother, Edith Robbins, toured the country as an actress. Mrs. Reagan later married Dr. Loyal Davis, and the family settled in Chicago.

Having caught the acting bug from her mother, young Nancy pursued the profession in New York and Hollywood, where she met with fellow actor Ronald Reagan. The two married on March 4, 1952.

The former Nancy Davis made 11 films in all, her last one coming in 1956: Hellcats of the Navy, co-starring her husband.

After her husband's election as governor of California in 1966, Mrs. Reagan began projects to assist wounded Vietnam veterans, prisoners of war, and service members missing in action. As first lady of the United States, Mrs. Reagan made drug abuse a central focus for her "Just Say No" program.

The library said that Mrs. Reagan is survived by her brother, Dr. Richard Davis; her two children with Ronald Reagan -- Patti Davis and Ronald Prescott Reagan -- as well numerous nieces and nephews.

In lieu of flowers, Mrs. Reagan had requested that memorial contributions be made to the Ronald Reagan Presidential Library and Foundation, the announcement said.

© Bill Hudson, ASSOCIATED PRESS Nancy and Ronald Reagan in 1975.