<human>:  What was the name of the first major sit-in at a lunch counter in the United States?
<bot>: The first sit-in at a lunch counter in the United States was the Greensboro sit-in. The sit-in was organized by four students at North Carolina A&T State University who were tired of being denied service at the Woolworth's lunch counter in Greensboro, North Carolina. They decided to protest by sitting down at the counter and refusing to move until they were served. The protest was successful and was followed by other sit-ins in the South.