"As directed by the City of Chicago, the Chicago Half Marathon event operations team implemented a required course change just prior to the start of the event, reducing the overall distance by 0.5 miles." - said the organizers.
Sorry, this sounds fishy to me. Did someone with the race not do all their permitting homework? The only time I have experienced a large race last-second course change like this is when the Army Ten Miler security forces spotted a suspicious package beside the course - later determined to be a bundle of trash. I see no report of any such security concerns in Chicago. Exactly what was the reason for the "required course change:?