The girl was forced into a vehicle in Bishop's Stortford at about 20:30 GMT on 16 February and dropped off near the town's railway station the following morning.
An E-fit image of the attacker has now been released.
Police said the attack had caused "concern within the community".
The girl was forced into a dark-coloured vehicle, thought to be a Land Rover, and taken to an unknown location, believed to be outside the county of Hertfordshire, where she was sexually assaulted.
Ch Insp Gerry McDonald of Hertfordshire Police said: "I believe local people hold the key to our investigation.
"This is an extremely serious matter and one which, understandably, has caused concern within the community.
"We have conducted a number of inquiries in the local area but would ask anyone who was around between the times mentioned and who has not yet spoken to police to contact us if you have any information which may assist our investigation.
"I would like to reiterate that this is an unusual incident and would reassure everyone that investigations into this incident are a priority."
Police are hunting for a man who raped a 14-year-old girl from Hertfordshire while holding her prisoner for nearly 12 hours overnight.