Sock hops were popular in high schools and other educational institutions, usually in the school gymnasium or cafeteria. The name arose as a result of dancers being compelled to remove their hard-soled shoes in order to maintain the gymnasium's varnished floor. As soon as they removed their socks, they would jump into the arms of their friends waiting outside the door for them. The first sock hops were held in 1913 at Detroit's Cass Technical High School during the off-season when students were not in class. The idea caught on quickly and within just five years, hundreds of sock hops had been held across the United States. By the late 1920s, adult sock hops were being held throughout the country as a way for employers to attract workers by providing food and entertainment for their events. In fact, one firm that made socks used the opportunity of a sock hop to announce its arrival in Detroit with a dance held in a church hall where attendees were asked to bring their own slippers. In 1967, a sock hop was held at Chicago's DePaul University to raise money for civil rights activists who had been shot by police officers during demonstrations against racial segregation. The event was organized by university students who wanted to show their support for their colleagues but also enjoy some fun after hours education. Today, a sock hop is any large party or social gathering held in someone's home or another location without a band or DJ.