The legendary boycott
of the Montgomery Alabama bus
system that was sparked by the arrest
of Rosa Parks
for refusing to give up her seat
to a white passenger
It was promoted by the Southern Christian Leadership Conference printing up something like 40,000 handbills and local religious leaders making announcements from the pulpit.
The boycott started in late 1955 and lasted well into 1956 when the Supreme Court declared segregated bus systems to be unconstitutional. While the boycott was on it was estimated that 90% of Blacks who normally rode the bus participated.
Of course, it wasn't as easy as that with Martin Luther King, Jr.'s house being bombed and efforts at carpooling met with baseballs and rocks.
One of the more important aspects of the boycott is that it showed Dr. King's methods to be effective and encouraged other civil rights groups to take part in non-violent actions. It was such a massive success and had such a high amount of participation in the Black community that it became a reference point for the effectiveness of non-violent activism.