Officials in Philadelphia announced a ban on backpacks at the upcoming Broad Street Run.
The announcement, made during a news conference on Wednesday, comes in the wake of the Boston Marathon bombings from earlier this month.
Mayor Michael Nutter said those at Sunday's race can expect to see more police officers and emergency staff as well.
Runners will also be impacted by the new security measures. Runners will have to place their belongings in clear, plastic bags.
The city says there are no specific threats targeting the event.