[2] The race was awarded the World Athletics Heritage Plaque in 2024, for "outstanding contribution to the history and development of road running.

[7][8] Those wishing to participate can register after either meeting a time qualifying standard or being selected through a general lottery.

[9] Although the race has limited registration, exceptions include elite runners, legacy finishers, and charity representatives.

[10] In the 21st century, increasingly, local, national and global charities as well as humanitarian organizations encourage sponsored participation in the event as a means of fund raising.

[11][12] The first modern marathon at the 1896 Games of the I Olympiad in Greece generated interest in the sport which led to similar races throughout most western countries and across the United States.

[17] In a stunning upset, a reported 100,000 or more spectators watched Chicagoan Rhud Metzner come from behind to steal a late-race victory from the favored Louis Marks.

[16] The second year, feet bleeding, Canadian Dennis Bennett won, while a band played "Maple Leaf Forever".

In the early years, runners had their own regimens: John Lindquist from Brooklyn took a commanding lead in 1907 while doing whiskey shots, but by mile 23, he was apparently falling asleep; while, the next year, the French-born Chicagoan Albert Corey had more success sipping champagne.

Frank Shorter's 1972 Games of the XX Olympiad marathon victory represented the convergence of many middle-class American ideals.

[4] Also that year, a group of runners in Chicago held a meeting at the YMCA on LaSalle Street to discuss interest and begin planning a local marathon.

[21] The Bank of America Chicago Marathon is an open race with no qualifying time to participate.

Although Mayor Daley died, his successor Michael Anthony Bilandic approved the race and got Kelly on board.

By 1982, the race finally had sufficient prize money to attract world class athletes.

The 1985 race was spectacular with Steve Jones breaking his own course record (2 seconds short of the world record) and Joan Benoit Samuelson the 1984 Olympic Champion, two-time defending Chicago Marathon Champion and Olympic Bronze Medalist, Rosa Mota and the fourth place Olympic finisher and world record setting Ingrid Kristiansen.

[29] The race resulted in three women who had been passed over for the 1988 Games of the XXIV Olympiad placing in the top positions.

[42] Over 10,000 registrants chose not to run in the record temperatures, while 10,934 people did not finish (many were called after the course closed early for safety).

[43][44] The 2020 edition of the race was cancelled due to the coronavirus pandemic, with all registrants given the option of either transferring their entry to 2021, 2022, or 2023, or obtaining a full refund.

Runners are supported by over 12,000 volunteers[48] spread throughout the course including at 20 aid stations[49] located approximate every 1–3 miles.

[50] For runners in distress, aid station volunteers include medical staff and ambulatory services are scattered throughout the course.

The 2001 marathon run on October 7 reached its cap of 37,500, which was instituted after the 2000 race drew 33,171 runners,[56] just prior to the entry deadline on September 19.

In 2001, Catherine Ndereba broke the record in 2:18:47, and Paula Radcliffe surpassed that mark with 2:17:18 the year after.

According to an independent study by the University of Illinois, the 2015 marathon contributed an estimated US$277 million worth of activity to the Chicago economy, equivalent to 1,948 jobs.

[71] Since the charity program was officially established in 2002, more than 106,000 runners have raised over $207 million for local, national and global causes.

[72] Charity fundraising is now closely intertwined with the event as the runners now raise money for research, aid the suffering and heighten public awareness of different causes.

[74] Runners can also opt out of the public lottery or obtain a guaranteed place after this has been drawn by choosing to run for an official charity.