Nearly 5,000 runners turned out to the very first Chicago Marathon, then named the Mayor Daley Marathon, on September 25, 1977. The attendance made the inaugural marathon the largest marathon in the world at the time.

In 2006, marathon organizers teamed with four other races in Boston, London, Berlin and New York to create a series of qualifying competitions worldwide. Tokyo was recently added to that list, creating six World Marathon Majors.

The Bank of America 2015 Chicago Marathon was held October 11 and featured nearly 50,000 participants.

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Read more about the history of the Chicago Marathon