Race organizers on Monday said that the times for 56 runners will be added to the list of official finishers after a problem with one of the electronic monitoring systems was found.
In order to prevent runners from skipping a portion of the race, checkpoints are scattered throughout the 26.2-course. Anyone who fails to be recorded passing two or more of the 11 checkpoints is disqualified.
But one of those checkpoints, at the 15 kilometer (9.3 mile) marker, failed on Sunday. Officials said that any runners whose time was not recorded at two consecutive checkpoints, included that faulty marker, will have their disqualifications overturned.
Approximately 4,000 runners were not recorded at the checkpoint, but only a few dozen were missed there and at an adjacent checkpoint.
Any runner who feels they have been incorrectly disqualified should call 312-904-9800 or send an e-mail to firstname.lastname@example.org.
This year's race was the 11th with the electronic monitoring system in place.
In 1980, a New York woman, Rosie Ruiz, had her medal from the Boston Marathon revoked after it was learned that she jumped into the race within the last mile and sprinted to the finish line.