Bobby Legrand Guinn was rushed to St. Luke's Hospital in critical condition after tumbling onto the tracks about 5:15 a.m., according to the NYPD.
He died a short time later, police said.
Guinn was found clutching $20 and $50 bills, and bills were also scattered on the tracks where he was struck, police sources said.
It was not immediately clear why Guinn was on the tracks, but police sources said they believed his death was an accident.
The investigation was ongoing Thursday afternoon.
Guinn, of Mary Esther, Fla., received his associate's degree from Northwest Florida State College in 2010, the school said.