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President Obama helped unveil a statue at the U.S. Capitol on Wednesday of activist Rosa Parks, whose 1955 refusal to give up her seat to a white man on a city bus in segregated Alabama was a pivotal moment in the civil rights movement.

Obama said Parks has taken her rightful place among those who have shaped the course of U.S. history. "We do well by placing a statue of her here, but we can do no greater honor to her memory than to carry forward the power of her principle and a courage born of conviction," he said.

Parks was arrested for not giving up her seat, touching off the Montgomery bus boycott that brought a young clergyman, the Rev. Martin Luther King, Jr. to national prominence as a civil rights leader.

Parks becomes the first black woman to be honored with a full-length statue in the Capitol's Statuary Hall. Her statue joins a bust of another black woman, abolitionist Sojourner Truth, which sits in the Capitol Visitors Center.

Rhea McCauley, Parks' niece, said there's plenty about her experiences that she deliberately withheld from her family to spare her nieces and nephews the horrible details surrounding her civil rights activism.

"They didn't talk about that stuff to us kids," said McCauley, 61. "Everyone wanted to forget about it and sweep it under the rug."

Jeanne Theoharis, author of the new biography "The Rebellious Life of Mrs. Rosa Parks," said Parks was very much a full-fledged civil rights activist, yet her contributions have not been treated like those of other movement leaders, such as King, who won the Nobel Peace Prize.

"Rosa Parks is typically honored as a woman of courage, but that honor focuses on the one act she made on the bus on Dec. 5, 1955," said Theoharis, a political science professor at Brooklyn College-City University of New York.

"That courage, that night was the product of decades of political work before that and continued ... decades after," she said.

Parks died Oct. 24, 2005, at age 92.

Parks was raised by her mother and grandparents, who taught her that part of being respected was to demand respect, said Theoharis.

She was an educated woman who recalled seeing her grandfather sitting on the porch steps with a gun during the height of white violence against blacks in post-World War I Alabama.

After she married Raymond Parks, she joined him in his work in trying to help nine young black men, ages 12 to 19, who were accused of raping two white women in 1931. The nine were later convicted by an all-white jury in Scottsboro, Alabama.

In the 1940s, Parks joined the National Association for the Advancement of Colored People and was elected secretary of the civil rights organization's Montgomery branch, working with civil rights activist Edgar Nixon to fight barriers to voting for blacks and investigate sexual violence against women, Theoharis said.

After the bus boycott, Parks and her husband lost their jobs and were threatened. They left for Detroit, where Parks was an activist against the war in Vietnam and worked on poverty, housing and racial justice issues, Theoharis said.

Parks has been honored previously in Washington with the Presidential Medal of Freedom in 1996 and the Congressional Gold Medal in 1999, both during the Clinton administration.

But McCauley said the Statuary Hall honor is different.

"The medal you could take it, put it on a mantel," McCauley said. "But her being in the hall itself is permanent and children will be able to tour the (Capitol) and look up and see my aunt's face."