On Feb. 1, 1960, four African American college students went into Woolworth's in Greensboro, North Carolina and sat at the lunch counter. They were refused service. They continued to sit at the counter that day. And the next. And the next. Their refusal to be dismissed became a 6-month sit in protest that culminated in the desegregation of the Woolworth's lunch counter.
From the Smithsonian site: