The accident occurred at 9:35 p.m. Monday on Route 13 (North DuPont Highway).
Police say 38-year-old Kimberly Cage of Delaware City was attempting to cross the northbound lanes of the highway from the center median when she was struck by a 2002 Mercedes-Benz M50 SUV.
Cage was pronounced dead at the scene.
Investigators say their preliminary findings indicate that where Cage attempted to cross was not within a designated or marked crosswalk.
The driver of the Mercedes was not injured in the incident and no charges have been filed.
Troopers continue to investigate the crash.