 The First Chicago Marathon was run on Saturday , September 23 , 1905 . That first race began in Evanston and finished in front of a standing @-@ room @-@ only paying crowd at Washington Park race track . In a stunning upset , a reported 100 @,@ 000 or more spectators watched <unk> Metzner come from behind to steal a late @-@ race victory from the favored Louis Marks . With that first race , the Chicago Marathon began an annual run of epic races that continued until the early 1920s on a revised course that largely resembles today 's marathon route . Over the years elite fields included Olympic champions , world records were continually sought , and the marathon continued to inspire Chicago communities and spectators until challenges of the early 1920s sidelined the event . 
