The 119th Penn Relay Carnival kicks off Thursday at Franklin Field on the campus of the University of Pennsylvania.
The event, which runs from Thursday to April 27, features the country's best runners from high school to college.
The college has increased security for the event, including a prohibition on backpacks or large bags and thorough security checks at every entrance.
"Security is always a high priority at the Penn Relays," Penn officials said in a statement last week. "It is something we take seriously, and given the situation in Boston, additional security measures will be undertaken during this year's games. We are not, however, going to discuss the specific details around security activities."