The first Chicago Marathon was run in 1905 from Evanston south through downtown Chicago to Washington Park. Only 15 participants started the race. For various reason, the classic Chicago Marathon didn't have staying power and fizzled by the early 1920s.
Over half a century would pass before the marathon would gain traction again. The 1960s heralded a more health-conscious culture and distance running was strongly correlated with a good ticker.
Following New York City's lead, Chicago instituted its first modern-era marathon in 1977. On September 25, 4,200 runners set out on the 26.2-mile race. Runners were charged a $5 registration fee, a trifle less than the $175 required today. The first race was sponsored privately by Lee Flaherty, a politically connected avid runner and owner of Flair Communications, a Chicago marketing agency.
The race started out at the Picasso sculpture in Daley Plaza, traveled north to Montrose Avenue, where runners turned south and traveled down to 55th Street; upon reaching 55th, runners turned north and returned downtown, finishing the race at Buckingham Fountain. The first runner to cross the finish line was 25-year-old Dan Cloeter, a theology student, who finished the race in 2:17.52. Dorothy Doolittle was the first woman to cross the line at 2:50.47.
The race has grown considerably over the years as it gained corporate sponsorship and starting attracting elite runners from all over the world. The 2013 marathon, sponsored by Bank of America, saw more than 39,000 runners finish the race, making it one of the largest marathons in the world.
For a complete description of the marathon's logistics, participants and changes over the years, check out The Chicago Marathon by Andrew Souzzo.