IO Theater has a branch in the United States.
Chicago ( [ ʃᵻˈkɑːɡoʊ ] or [ ʃᵻˈkɔːɡoʊ ] ) , officially the City of Chicago , is the third-most populous city in the United States . iO , or iO Chicago , ( formerly known as `` ImprovOlympic '' ) is an improv theater and training center in central Chicago , with a branch in Los Angeles called iO West .