Illinois Official Dance: The Square Dance

In 1990, Governor Thompson signed into law a bill designating the Square Dance as the American folk dance of the State. Square Dance is a term used to describe many individual dances done in a style that traces its origins back to Morris dancing in England and French dancing with influences of Irish, Spanish, and Scottish dancing thrown in. It was revived in the 1950s and remains a popular pastime.
Below are some links where you can learn more about square dancing and its history.

References:

http://www.heritagedance.com/articles.html Links on the history of square dancing http://www.squaredancing.com/ SquareDancing.com site includes discussion forums, calendar, and databases.
http://www.dosado.com/clubsorgs/default.htm listing of state and international square dancing clubs
http://www.squaredance.ws/ The Northeast Square Dancer Magazine
http://www.netstate.com/states/symb/dances/il_square_dance.htm History of square dancing