“Starting this year, all registered runners must pick up their own participant packets, which include their event-issued bib numbers and other race-related and promotional material. In past years, individuals could pick up packets on behalf of others. All individuals entering Grant Park on race day will have to go through one of four designated security and bag screening checkpoints. Spectators are discouraged from carrying bags into the park, and runners will only be able to carry a clear, plastic event-issued bag — designed to speed security screening.”
http://www.rawstory.com/rs/2013/08/29/chicago-marathon-ups-security-after-boston-bombings/