"Mrs. Parks's arrest was the precipitating factor rather than the cause of the protest," Dr. King wrote in his 1958 book, "Stride Toward Freedom. "The cause lay deep in the record of similar injustices."

Her act of civil disobedience, what seems a simple gesture of defiance so many years later, was in fact a dangerous, even reckless move in 1950's Alabama. In refusing to move, she risked legal sanction and perhaps even physical harm, but she also set into motion something far beyond the control of the city authorities. Mrs. Parks clarified for public consumption far beyond Montgomery the cruelty and humiliation inherent in the laws and customs of segregation.

That moment on the Cleveland Avenue bus also turned a very private woman into a reluctant symbol and torchbearer in the quest for racial equality and of a movement that became increasingly organized and sophisticated in making demands and getting results....

In "Stride Toward Freedom," Dr. King wrote:

"Actually no one can understand the action of Mrs. Parks unless he realizes that eventually the cup of endurance runs over, and the human personality cries out, 'I can take it no longer.' Mrs. Parks's refusal to move back was her intrepid affirmation that she had had enough. It was an individual expression of a timeless longing for human dignity and freedom. She was not 'planted' there by the N.A.A.C.P. or any other organization; she was planted there by her personal sense of dignity and self-respect. She was anchored to that seat by the accumulated indignities of days gone by and the boundless aspirations of generations yet unborn."

The boycott was precipitated by Rosa Parks's refusal to give up her bus seat in favor of a white passenger. In Montgomery, the dividing line between the front seats reserved for white passengers and the back ones reserved for black passengers was not fixed. When the front of the bus was full, the driver could order black passengers sitting towards the front of the bus to surrender their seat. Rosa Parks's seat was in that border area. She was arrested on Wednesday, December 1, 1955, for her refusal to move.... When found guilty later, she was fined $10 plus a court cost of $4, but she appealed.

On Thursday, December 9, 1955, Jo Ann Robinson would receive a call from Fred Gray, one of the city's two black lawyers, informing her that Rosa Parks had been arrested. That entire night Robinson worked tirelessly mimeographing over 35,000 handbills reading:

"Another Negro woman has been arrested and thrown into jail because she refused to get up out of her seat on the bus for a white person to sit down. It is the second time since the Claudette Colbert case that a Negro woman has been arrested for the same thing. This has to be stopped... "The woman's case will come up on Monday. We are therefore asking every Negro to stay off the buses Monday in protest of the arrest and trial. Don't ride the buses to work, to town, to school, or anywhere on Monday..."

The next morning at a church meeting with the new minister in the city, Martin Luther King, Jr., a citywide boycott of public transit as a protest for a fixed dividing line for the segregated sections of the buses was proposed and passed.

The boycott proved extremely effective, with enough riders lost to the city transit system to cause serious economic distress. Instead of riding buses, boycotters organized a system of carpools, with car owners volunteering their vehicles or themselves driving people to various destinations. Some white housewives also drove their black domestic servants to work, although it is unclear to what extent this was based on sympathy with the boycott, versus the simple desire to have their staff present and working. When the city pressured local insurance companies to stop insuring cars used in the carpools, the boycott leaders arranged policies with Lloyd's of London.

Black taxi drivers charged ten cents per ride, a fare equal to the cost to ride the bus, in support of the boycott. When word of this reached city officials, the order went out to fine any cab driver who charged a rider less than 45 cents. In addition to using private motor vehicles, some people used nonmotorized means to get around, such as bicycling, walking, or even riding mules or driving horse-drawn buggies. Some people also hitchhiked around. During rush hours, sidewalks were often crowded, but buses received extremely few, if any, passengers. Across the nation, black churches raised money to support the boycott and collected new and slightly used shoes to replace the tattered footwear of Montgomery's black citizens, many of whom walked everywhere rather than ride the buses and submit to Jim Crow.

In response, opposing whites swelled the ranks of the White Citizens' Council, the membership of which doubled during the course of the boycott. Like the Ku Klux Klan, the Councils sometimes resorted to violence: Martin Luther King and Ralph Abernathy's houses were firebombed, and boycotters were physically attacked.

Under a 1921 ordinance, 156 protestors were arrested for "hindering" a bus, including King. He was ordered to pay a $1,000 fine or serve 386 days in jail. The move backfired by bringing national attention to the protest. Eventually, the United States Supreme Court affirmed a lower court decision that Alabama's racial segregation laws for buses were unconstitutional, handing the protesters a clear victory. This victory led to a city ordinance that allowed black bus passengers to sit virtually anywhere they wanted. Martin Luther King capped off the victory with a magnanimous speech to encourage acceptance of the decision.