18 events were there in Chicago Marathon . 12 were the number of teams who competed in Chicago Marathon . It was held in 19–20 August . Tennis Club de Paris, at Auteuil (some of the years 1895–1908),Chicago, Illinois, United States,Arena Olímpica do Rio were the venues of Chicago Marathon . 37 from 31 nations were the competitors in Chicago Marathon . The official site of Chicago Marathon is www.hardrock100.com . 1891; 128 years ago (1891) is when Chicago Marathon was established 
More than 23 events were held in Chicago Marathon