Team USA ends the World U20 Champs with another relay sweep! 4x400m champs running 3:02.39 & 3:29.11! 🇺🇸😈💯 . . . . #MileSplit #track #tracknation #goals #squadgoals #running #relay #usa #teamusa #worldjuniors #usatf #bydgoszcz2016