The event that marked the early civil rights movement in America was the Montgomery Bus Boycott, initiated in 1955. Sparked by Rosa Parks' refusal to give up her seat to a white passenger, the boycott lasted for over a year and was characterized by the organized resistance of African Americans in Montgomery, Alabama. It aimed to combat racial segregation in public transportation. The success of the boycott was significant, ultimately leading to a Supreme Court ruling that declared such segregation unconstitutional. This movement galvanized further activism and set the stage for broader civil rights advancements throughout the 1960s.