An American pastime in rural places where -- gasp -- dancing was considered a sin. So the young people of courting age got together to play games instead. Which might involve music. And pairing off the girls and boys. And moving about in rhythmic patterns. But it's a game, not dancing.
There were some differences. The music was sung by the dancers. Some of his informants told of play-parties with instruments, but most agreed that instruments moved it over to the dancing arena. (Particularly the fiddle, the most diabolic of instruments.) You swung by holding your hands high, palms together. No drinking allowed. Kissing games were often disallowed.
About a third of the book is the account of the practices -- one did not invite people but spread the news, so everyone was welcome; some people objected to Weevil Wheat because it was not even concealed Virginia Reel; the differences between children's and more difficult adult games -- and the rest is a listing of songs (with music) and the steps to them.