16 (from 6 confederations) were the number of teams who competed in Chicago Marathon . 1891; 128 years ago (1891) is when Chicago Marathon was founded  . The official site of Chicago Marathon is www.hardrock100.com . 18 from 18 nations were the competitors in Chicago Marathon . It was held in 28 July – 9 August . London Velopark (BMX, track),Chicago, Illinois, United States were the venues of Chicago Marathon
The sport Chicago Marathon has 18 contenders  from less than 25 nations