Some years ago, flash mobs were popular among young people in the U.S., but in China, they became square dancers. The U.S. is sparsely populated, the community structure is complex, the elderly generally do not live in the city, and look at the young people dancing flash mob is very nice to see, look at the big moms dancing in the square is very annoying, as a majority of highly educated countries American women do not need to make a fool of themselves.