What is an overdrive transmission

Before the invention of the overdrive transmission, the final gear would always be direct drive(1:1 gear ration).  So, you had to choose what you wanted out of your car.  This meant that all but the most aggressive cars came from the factory with “highway gearing”.  Highway gearing tended to be like a 2:73 axle ratio, or something close.  It was a compromise in all directions, but there was no clear solution to fix the problem.  Also, gas was cheap so it didn’t matter so much to the big three(or consumers) just how fuel efficient you car was.  The car would take off sluggish and pull a lot of RPM’s on the highway.  The overdrive transmission eliminated all of these compromises.