Boggs, who later served three years as ambassador to the Vatican during the Clinton administration, died of natural causes at her home in Chevy Chase, Md., according to her daughter, ABC News journalist Cokie Roberts.
Boggs' years in Congress started with a special election in 1973 to finish the term of her husband, Thomas Hale Boggs Sr., whose plane disappeared over Alaska six months earlier. Between them, they served a half-century in the House.
"It didn't occur to us that anybody else would do it," Roberts said in explaining why her mother was the natural pick for the congressional seat. Her parents, who had met in college, were "political partners for decades," she said, with Lindy Boggs running her husband's political campaigns and becoming a player on the Washington political scene.
Roberts called her mother "a trailblazer for women and the disadvantaged."
When Boggs announced her retirement in 1990, she was the only white representing a black-majority district in Congress. "I am proud to have played a small role in opening doors for blacks and women," she said at the time.
As family tragedy brought her in to Congress, so did it usher her out. At the time of her July 1990 announcement, her daughter Barbara Boggs Sigmund, mayor of Princeton, N.J., was dying of cancer. Sigmund died that October.
Her son, Thomas Hale Boggs Jr., is a leading Washington lawyer and lobbyist.
The elder Boggs was first elected to Congress in 1940, two years after the couple married. Both were also active in local reform groups.
Lindy Boggs was more than the typical congressional wife. She ran several of her husband's political campaigns and helped him in his Washington and New Orleans offices.
"Early on, Hale established with politicians at home that I was his direct representative and that they could say anything to me that they could say to him. Whatever decisions I made, they would be his final decisions," she said in 1976.
Breaking with most Southern whites, Lindy Boggs saw civil rights as an inseparable part of the political reform movement of the 1940s and '50s.
"You couldn't want to reverse the injustices of the political system and not include the blacks and the poor. It was just obvious," she said in 1990.
She worked for the Civil Rights Acts of 1965 and 1968, Head Start and other programs to help minorities, the poor and women.
After she entered Congress, Boggs used her seat on the House Appropriations Committee to steer money to New Orleans and the rest of the state. As a member of the House Banking and Currency Committee, she used typical steely grace to include women in the Equal Credit Opportunity Act of 1974.
"I ran into a room where there was a copying machine, wrote in 'sex and marital status' on the bill, and made 47 copies," she said. "When I took it back into the subcommittee meeting, I told them I was sure it was just an oversight on their part."
Boggs changed the way politics operated, former Sen. J. Bennett Johnston, D-La., once said.
"I've seen it time after time," Johnston said. "On difficult issues, powerful men and women are going toe to toe, sometimes civilly, sometimes acrimoniously. Lindy Boggs will come into the room. The debate will change. By the time she leaves the room, she usually has what she came to get."
As the first woman to chair the Democratic National Convention, in 1976, she decreed that she would be addressed as "Madam Chairwoman," rather than "Madam Chairman" or "Madam Chairperson."
"I'm a woman," she said. And, "Why should it be neuter?"
When Hurricane Katrina devastated New Orleans in 2005, one of the hardest-hit facilities was Lindy Boggs Medical Center, a historic hospital named in her honor the previous year.
Her Bourbon Street home also was damaged and The Washington Post reported in February 2006 that she was living in a hotel nearby.
"There are worlds of friends I miss," she told the newspaper. "The culture is not there."
Corinne Claiborne was born March 13, 1916, on a plantation near New Orleans, a descendant of William C.C. Claiborne, the state's first elected governor. She came to be known as Lindy, according to Roberts, because a nurse thought she looked like her father, Roland Claiborne, and called her "Rolindy."
She attended Sophie Newcomb College, affiliated with Tulane University, and met her future husband when both were editors of the Tulane student paper. She taught school between graduation in 1935 and their marriage in 1938.
As part of a group of well-connected women called the Independent Women's Organization, she took to the street in a "Broom Brigade" in 1945, sweeping the streets to publicize the need to sweep out graft and corruption.
In her first election for Congress, in March 1973, she had to overcome prejudice against her gender and privileged background.
Said her Republican opponent, Robert E. Lee: "I've covered this district by foot, by car, by air. This is something that takes a strong, healthy man. ... A socialite is not going to do this district any good in Congress."
Her constituents disagreed, giving her at least 60 percent of the vote in every election from then on.
In 1991, a room in the Capitol for female members of Congress was renamed the Lindy Claiborne Boggs Congressional Women's Reading Room to honor her long association with Congress. According to the House website, it was the first, and only time so far, that a room in the Capitol has been named for a woman.
Her Vatican posting was from 1997 to early 2001, and she said her goals were to work with the Vatican on promoting democracy, tolerance, religious freedom, peace and human rights.
In 2000, she announced that she would resign after President Bill Clinton left office, no matter which party won. "It's been an honor and a privilege and a wonderful opportunity to be in this position, but it's also extremely exhausting," she said at the time.
Clinton and his wife, former Secretary of State Hillary Rodham Clinton, said in a statement that Boggs possessed "a keen intelligence and enduring charm," and was "a true original" who was "as graceful as she was effective."
"The country has lost a champion for civil rights and a trailblazer for women," the said.
In addition to her children, Boggs is survived by eight grandchildren and 18 great-grandchildren.