The tree toppled while the drivers were traveling along Lancaster Avenue near Stanford Drive around 1:45 p.m. on Sunday.
First responders extricated the two women from the vehicles. They were then taken to Lankenau Hospital.
Lancaster Avenue was closed between Remington Road and Clover Hill Road for approximately five hours while officials investigated the incident
The crash remains under investigation by the Lower Merion Township Police Department's Traffic Safety Unit.
The identity of the woman killed has not yet been released.