The earliest and oldest remaining role of the first lady is that of hostess. But there is more to even that job than simply greeting guests.
"It's not just throwing a dinner party," says Allida Black, Project Director and Editor of the Eleanor Roosevelt Papers at George Washington University. "What the role of the first lady is there (at a White House dinner party), is to understand the politics of Washington and make sure that people at the table get done the work that that dinner is supposed to accomplish."
That responsibility dates back to the first, first lady, Martha Washington. She set another precedent, when she became an ardent supporter of Revolutionary War veterans, says Smithsonian curator Graddy. "Now, with first ladies, there is always a cause they espouse, usually one that is very personal to them." Advocating a cause
In the early 1960s, Jacqueline Kennedy restored historic furnishings to the White House. Lady Bird Johnson, her immediate successor, campaigned for highway beautification with the planting of wildflowers and helped launch the Head Start program for early child development.
Betty Ford was a vocal supporter of the Equal Rights Amendment and, as a cancer survivor, a voice for breast cancer awareness.
Nancy Reagan campaigned against drug abuse. Barbara Bush advocated for literacy, as has her daughter-in-law, Laura Bush. The outgoing first lady has also become increasingly vocal on behalf of women worldwide.
"I think the first lady can send a strong signal to people not just in the United States," says Allida Black, "but all around the world about what a powerful woman's voice can mean in government."
First ladies have long served as unofficial ambassadors abroad. Eleanor Roosevelt was the first, in the 1940s. She also traveled extensively around the United States after her husband became president in 1933. "She felt her role was to really reach out to the American people and to learn from them what they wanted in policy that could make their lives better," Black says.
As first lady, Hillary Clinton was also intimately involved in policy. Days after his inauguration, Bill Clinton appointed her to chair a committee on health care reform.
The influence of other first ladies has been less public. Historian Carl Sferazza Anthony, of the National First Ladies' Library, has written several books on first ladies. He says Nancy Reagan was instrumental in improving relations between the United States and the former Soviet Union when Mikhail Gorbachev became its president. "She felt very strongly that there might be an opportunity there for her husband to strike up a personal friendship which might lead to a greater understanding between the two superpowers, and which might in fact - and did - lead to a reduction in nuclear armaments. Anthony says Reagan implored and encouraged not only her husband, but also representatives of the Soviet government and the Secretary of State to encourage dialogue between the leaders.
During the recent presidential election campaign, when Senator Hillary Clinton launched her own bid for the White House, Americans wondered: what would become of the role of first lady when a woman becomes president? American history scholar Carl Sferazza Anthony says former president Bill Clinton gave an example through his activities on behalf of AIDS awareness and global relief efforts after the tsunami in Indonesia.
Whether a man or a woman, Americans have certain expectations of the first spouse. "You want the first lady or first gentleman to give them [the president] the moral support that your own spouse gives you," says Allida Black, "but at the same time, you expect them to be smart, tough, put the country first, not have their own ego get in the way, and be able to roll up their sleeves and work."
Michelle Obama will no doubt discover, in the weeks and months ahead, how she can meet the needs of the president and the nation as first lady. Historian Carl Sferrazza Anthony predicts, she will most likely be changed by her new position. "Because you are exposed to the most extraordinary circumstances domestically and internationally, you can't help but grow in your understanding of the world and its problems and want to do something about it."