The Chicago Mustangs were charter members of the United Soccer Association (USA) in 1967. The league was made up if wholly imported European teams, The Mustangs were actually??Cagliari Calcio??from Italy. In 1968, the USA merged with the National Professional Soccer League (NPSL) to form the The Mustangs left the league and went semi-pro in 1969. They eventually became a feeder team for the who joined the NASL in 1974.