Runners in the 2007 Chicago Marathon

The Chicago Marathon is a major marathon held yearly in Chicago in Cook County, Illinois, United States. Alongside the Boston, New York, London and Berlin Marathons, it is one of the five World Marathon Majors.

The first race was held on September 25, 1977 under the original name the Mayor Daley Marathon, and drew a field of 4200 runners. The race has been held every year since, except in 1987 when only a half-marathon was run. It is among the fastest growing marathon road races in the world, due in part to its largely fast and flat course which facilitates the pursuit of personal records and world record performances. The race has achieved its elite status among marathons by developing relationship with sponsors who provide prize money to lure elite runners who have produced American and world record performances.

There is no qualifications required to participate in the Chicago Marathon, but only runners who finish within 6½ hours are officially timed. The 1982 marathon was the first with world class times such as the 2:10:59 by Greg Meyer, the last American-born male to win the race. The race is currently limited to 45,000 runners on a first-come, first-served basis. Although the race has limited registration, exceptions include elite runners and charity representatives. Increasingly, local, national, and international charities and humanitarian organizations encourage sponsored participation in the event as a means of fund raising.

World records have been broken at Chicago four times. In 1984, Steve Jones broke the world record with 2:08:05. In 1999, Khalid Khannouchi was the first to surpass 2:06:00 with 2:05:42. The women's record was broken in two consecutive years. In 2001, Catherine Ndereba broke the record in 2:18:47, and Paula Radcliffe surpassed that mark with 2:17:18 the year after. Radcliffe's world record is also the course record; while the men's record is 2:04:38, set in the 2012 race by Tsegaye Kebede.