The accident happened about 5:35 p.m. on U.S. 13 (DuPont Parkway) at Fieldsboro Road.
Police said Bonnie A. King, 65, of Middletown, was making a left turn from southbound U.S. 13 in her 2011 Hyundai Sonata.
She was struck on the right side by the front of a northbound 2015 Kia Rio, driven by Bryant A. Gilliam, 38, of Newark.
The Hyundai ended up in a ditch, and the Kia stopped in the northbound lanes.
King was taken by state police helicopter to Christiana Hospital, with injuries said were not life-threatening.
She was cited by troopers for failing to yield the right-of-way.
Gilliam was taken by ambulance to Christiana for treatment of injuries not considered life-threatening, police said.
The crash closed the northbound lanes of U.S. 13 about an hour.