The USA Red team ran a time of 3 minutes, 22.66 seconds, with Jessica Beard, Natasha Hastings and Dee Dee Trotter preceding McCorory on the unit, and helped the United States post a 4-2 record in the six races.
A 4x800-meter relay team anchored by Olympian Alysia Montano obliterated the American record in the event by more than 13 seconds, in a time of 8:04.31. Lea Wallace, Brenda Martinez and Ajee Wilson ran the first three legs.
The Americans also took the men's 4x100 in 38.26 seconds and the men's 4x400 in 3:00.91. But Jamaica, behind a fantastic anchor leg from two-time Olympic gold medalist Shelly-Ann Fraser-Pryce, broke the eight-year streak of the United States in the women's 4x100, winning in 42.42 seconds with the wave of noise from the Jamaican fans in the stadium seeming to carry her home.
Ethiopia came home first in the men's distance medley relay in 9:16.34 thanks to a potent kick in the final 150 meters by Aman Wote.
McCorory and Trotter were members of the U.S. gold medal-winning 4x400 relay last year at the London Olympics. Of the other two runners, Allyson Felix decided to run just one event at the Penn Relays, the 4x100, while Sanya Richards-Ross is recovering from a toe injury.
Trotter, the veteran of the team at 30, said that while it's early in the season, the Penn Relays is a good place to start serious preparation leading up to the U.S. trials in June for the World Track and Field Championships, beginning Aug. 10 in Moscow.
"We use the Penn Relays as an opportunity to build some team chemistry," she said. "At the same time we use it for training. We really haven't run many [individual] 400s between all of us. Our preparation is definitely geared toward the outdoor trials for our World Championships team."
One U.S. team on the women's 4x100 included three of the four athletes who set a world record in the event in winning Olympic gold last year. But that team, with Tianna Madison Bartoletta, Felix, and Bianca Knight running the first three legs, placed third on Saturday.