I went to my first dance at the prompting of a friend whose band was playing for a dance. Everyone started each dance with a partner, but danced with everyone in the line during the course of each individual dance. Each dance would last about 5-10 minutes and there would be a little over an hour's worth of dances in each set. There would be a break, and then the dancing would start again.
Most contra dances last a total of about three hours.
He further explained that while there are always some couples at these dances, many of the people are single. I ventured out one December night to a local community center. I paid my admission and walked into the hall where about a dozen people were just starting to gather in the center of the room with the instructor. And then the music started. As an amateur genealogist, I realized that my ancestors had likely done these dances in Scotland and Ireland years before me, and I felt that somehow, somewhere I had done all this before .