On this day in 1955, Rosa Parks broke the law by refusing to give up her seat to a white man on a city bus in Montgomery, Alabama, resulting in her arrest. At the time, she said that she was just too tired to stand that day, but she later admitted that she’d challenged the law on purpose because she thought it was wrong. She recalled, “When that white driver stepped back toward us, when he waved his hand and ordered us up and out of our seats, I felt a determination cover my body like a quilt on a winter night.” She refused to give up her seat. “When he saw me still sitting, he asked if I was going to stand up, and I said, ‘No, I’m not.’ And he said, ‘Well, if you don’t stand up, I’m going to have to call the police and have you arrested.’ I said, ‘You may do that.’”

Parks’s arrest was the catalyst that the newly formed Montgomery Improvement Association needed to organize a boycott of the city’s buses on December 5. A 26-year-old pastor named Martin Luther King, Jr. emerged as the protest’s leader; on the first night of the boycott he came forward and said, “The great glory of the American democracy is the right to protest for right.”

The boycott of the buses in Montgomery continued for over a year and eventually helped lead to the end of segregation.