The singe vehicle collision happened at around 7pm on Thursday 18 September 2014, at Kex Gill Farm near Hazlewood, between Skipton and Harrogate.
A white Seat Ibiza, which was travelling towards Harrogate, left the road and rolled down an embankment several times before coming to rest on moorland opposite the farm.
The 19-year-old woman driver of the car was taken to Airedale Hospital with a suspected, serious back injury. The male passenger sustained minor injuries. Both the driver and the passenger are from Harrogate.
Police are appealing for witnesses to the collision, in particular, they would like to trace a woman who stopped at the scene of the crash to help the occupants of the car.
Police also want to hear from anyone who noticed the white Seat travelling along the A59 or who saw the collision happen.
If you stopped at the scene or have any information which could assist the investigation, please contact North Yorkshire Police on 101, select option 2 and ask for Traffic Constable David Minto. Or email firstname.lastname@example.org
Please quote reference number 12140160523 when passing on information.