 The Chicago Marathon is entered by predominantly Caucasian entrants from middle- to upper @-@ middle @-@ class affluence with a wide range in age and near equality in the sexes . The Chicago Marathon has never excluded women . Historically , however , the women 's field has been smaller than the men 's . This seems to be the result of older age categories having large multiples of men to women , but the women are beginning to outnumber the men in the 20s age group of the field . 
