Due to the rising heat index and higher than expected temperatures, LaSalle Bank Chicago Marathon Executive Race Director Carey Pinkowski and Medical Director Dr. George Chiampas, in cooperation with city officials, have implemented a contingency plan, as a precautionary measure, to effectively close the Marathon course at the halfway point. Runners who have not reached the halfway point by approximately 12:00 p.m. will be diverted back to Grant Park via Halsted and Jackson. Jackson will be closed to automobile traffic and the participants will be provided with additional support along this route. Participants who crossed the halfway point prior to the shut-down will continue to be fully supported along the standard course to the finish line. Participants are asked to take advantage of medical personnel, cooling buses, runner drop out buses, water, Gatorade and other means of support en route back to Grant Park.
And according to the Chicago Sun-Times, it was cancelled at 11:45 a.m.