 Société Athlétique de la Villa Primrose in Bordeaux (1909) were the venues of Chicago Marathon . It was held in 1 August . The official site of Chicago Marathon is www.hardrock100.com . 24 (from 5 confederations) teams participated in Chicago Marathon . 28 from 21 nations competed in Chicago Marathon . 12 events were there in Chicago Marathon . 5 September 1971 is when Chicago Marathon was founded 
Chicago Marathon will celebrate it's  Diamond jubilee on 2031