Electronic Route Guidance System ( ERGS ) was a 1970s government sponsored in-vehicle navigation and route guidance system used in the United States . ERGS was the first stage of a larger research and development effort called the Intelligent Transportation System (ITS). Other programs include Japan’s CACS and similar projects in Europe.
ERGS was a destination oriented system that required a human driver to enter a destination code into the vehicle system. The vehicle communicated with an instrument intersection where the destination code was decoded and routing information was sent back to the vehicle. 
- Jump up^ Rosen, DA, Mammano, FJ Favout, R. (1970). An electronic road-guidance system for highway vehicles. IEEE Transactions on Vehicular Technology. (19) 1: 143-152.