Michelle Obama; first lady; photo wallpapers: Michelle Obama Tuesday stepped into a long and illustrious line of
US first ladies, adopting an unpaid role with no official duties, even
though she is likely to wield considerable sway.

As the first
African American woman to take up the post as the nation's top hostess,
Obama can look back through history to see how other women shaped their
role and her destiny.

Since Martha Washington reluctantly debuted
the role in 1789, a varied parade of American women has transformed the
position along the way: from national hostess, to White House manager,
behind-the-scenes policy advisor or public advocate of favorite causes.

Vivacious
Dolley Madison (1809-1817), a celebrated hostess and fashion-setter,
refused to leave the White House until a portrait of George Washington
was taken to safety when British troops burned Washington during the
War of 1812.

Mary Lincoln (1861-1865) lived one of the most
tragic chapters in the role's history, seeing her 11-year-old son
Willie die of disease in the White House and her husband shot dead. She
later slipped into madness and died, impoverished, in 1882.

The
gifted and ambitious Hellen Taft (1909-1913) was the first in the role
to advocate women's voting rights, not established in the United States
until 1920. She also replaced the White House corps of all-white male
ushers with African-Americans.

When a stroke left Woodrow Wilson
(1913-1921) partly paralyzed in 1919, his wife of four years, Edith
Wilson, "took over many routine duties and details of government," her
official White House biography says.

Eleanor Roosevelt
(1935-1945) eschewed the duties of running the White House and became
one of the most active first ladies ever, travelling across the United
States and the world speaking on issues of the day, notably civil
rights.

Michelle Obama's fashion know-how has some calling her
"Michelle O," in their eyes the rightful successor to former John F.
Kennedy's wife, Jacqueline Kennedy Onassis (1961-1963), who charmed
with her glamour and beauty.

Obama is one of the youngest first
ladies to enter the White House after "Jackie O," who remains one of
the most popular first ladies in US history.

Betty Ford
(1974-1977) further transformed the role through her public battles
with alcoholism and breast cancer and her outspoken advocacy of women's
rights.

Hillary Clinton, whom Obama has chosen as his secretary
of state, became the first American woman to mount a viable run for
president, leading a fierce and ultimately losing battle for the 2008
Democratic presidential nomination.

While first lady (1993-2001),
she also took a pioneering role in fashioning national policy, leading
an ultimately doomed effort to reform the US health care system.

Former first lady and self-professed book worm Laura Bush initially used her position to encourage child literacy.

But
-- over eight years in the White House, during which her popularity
waxed while her husband's waned -- she went on to exert influence in
causes like the fight against heart disease in women and the promotion
of girls' education in Afghanistan.

Obama has said that she intends first and foremost to take care of her daughters, Malia 10 and Sasha, seven.

But
the Princeton and Harvard-educated lawyer from a working class Chicago
background, who has only just resigned from her job as the vice
president of the University of Chicago medical center, could well
decide to take a more actively political role.