"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" in Detroit, she said.
Parks died Oct. 24, 2005, at age 92. The U.S. Postal Service issued a stamp in her honor on Feb. 4, which would have been her 100th birthday.
Parks was raised by her mother and grandparents who taught her that part of being respected was to demand respect, said Theoharis, who spent six years researching and writing the Parks biography.
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, Ala., part of a long legal odyssey for the so-called Scottsboro Boys.
In the 1940s, Parks joined the NAACP and was elected secretary of its Montgomery, Ala., branch, working with civil rights activist Edgar Nixon to fight barriers to voting for blacks and investigate sexual violence against women, Theoharis said.
Just five months before refusing to give up her seat, Parks attended Highlander Folk School, which trained community organizers on issues of poverty but had begun turning its attention to civil rights.
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.