Investigators say 15-year-old Christiana Townsley of Manheim, Pa. was trying to cross the westbound lanes of Pulaski Highway (Route 40), west of Quintillo Drive, at about 9:30 p.m.
As she ran north from the grass median onto the roadway, police say, she was struck by a 2008 Nissan Altima, which was traveling westbound in the center lane.
The Nissan was driven by Katelyn Nelson, 25, of Elkton, Maryland.
Townsley was taken to Christiana Hospital Trauma Center where she died overnight.
Police say Nelson was wearing a selt belt and was not injured. She stopped after the accident happened and has not been charged.
The westbound lanes of Pulaski Highway were closed for approximately 1.5 hours while the crash was investigated and cleared.