As told by the Library of Congress:
On the evening of December 1, 1955, Rosa Parks, an African American, was arrested for disobeying an Alabama law requiring black passengers to relinquish seats to white passengers when the bus was full. Blacks also were required to sit at the back of the bus. Her arrest sparked a 381-day boycott of the Montgomery bus system and led to a 1956 Supreme Court decision banning segregation on public transportation.
Rosa McCauley was born on February 4, 1913, in Tuskegee, Alabama. In 1932, she married Raymond Parks and with his encouragement earned a high school diploma. The couple was active in the Montgomery Chapter of the National Association for the Advancement of Colored People (NAACP). While working as a seamstress, Mrs. Parks served as chapter secretary and, for a time, as advisor to the NAACP Youth Council. Denied the right to vote on at least two occasions because of her race, Rosa Parks also worked with the Voters League in preparing blacks to register.
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Although her arrest was not planned, Park’s action was consistent with the NAACP’s desire to challenge segregated public transport in the courts. A one-day bus boycott coinciding with Parks’s December 5 court date resulted in an overwhelming African-American boycott of the bus system. Since black people constituted seventy percent of the transit system’s riders, most busses carried few passengers that day.
The success of the boycott mandated sustained action. Religious and political leaders met at the Dexter Avenue Baptist Church and formed the Montgomery Improvement Association (later the Southern Christian Leadership Conference). Dexter’s new pastor, Reverend Martin Luther King Jr., was appointed the group’s leader. For the next year, the Montgomery Improvement Association coordinated the bus boycott and King, an eloquent young preacher, inspired those who refused to ride:
If we are wrong—the Supreme Court of this nation is wrong. If we are wrong—God almighty is wrong! If we are wrong—Jesus of Nazareth was merely a utopian dreamer and never came down to earth. If we are wrong—justice is a lie. And we are determined here in Montgomery to work and fight until justice runs down like water and righteousness like a mighty stream.Reverend Martin Luther King, Jr., Montgomery, Alabama, 1955.