18 events were there in Chicago Marathon . April 23–29 was when it was held . Paris, XVIe,France were the venues of Chicago Marathon . 28 from 28 nations were the competitors in Chicago Marathon . 16 (from 6 confederations) were the number of teams who competed in Chicago Marathon . Chicago Marathon was established on 2005 . The official site of Chicago Marathon is www.hardrock100.com
28 nations took part in Chicago Marathon