It happened just after 6:30 am on Elm Avenue north of Manning Avenue, south of Easton.
Investigators believe the woman tried to make a U-turn when she lost control of the vehicle. The victim tried to get out, but the car crashed into a tree, leaving the driver pinned between her car and the door.
She was pronounced dead at the scene.
The CHP is working to determine whether the driver may have suffered a medical emergency. Her name has not been released.