A Sunday in April 1961 (“The Beatnik Riot”)
(Image from NPR. Click on the image to see their report on the story.)
On April 9, 1961, folk singers who had been rejected a permit to sing in Washington Park, NY, took to the park to express their position. They sang folk songs, and the police began taking them away. NPR says this protest had lasting significance as one of the first US protests of the 1960s.
A documentary entitled Sunday was filmed that day by Dan Drasin and was made into a 17 min 9 sec film that you can see on his site. I highly recommend it.