16 (from 6 confederations) were the number of teams who competed in Chicago Marathon . London Velopark (BMX, track),Chicago, Illinois, United States were the venues of Chicago Marathon . 1891; 128 years ago (1891) is when Chicago Marathon was founded  . 28 July – 9 August was when it was held . The sport has the official site www.hardrock100.com . 18 from 18 nations competed in Chicago Marathon
Less than 2 nations participated in the event