Many satellites (such as the recent Iridium launch) need to be in either slight retrograde or polar orbit. Since Kennedy Space Center is located on the east coast of Florida, rockets that need to go west or north/south have to be launched from Vandenberg in California.
Also, during the early days of the Shuttle, it had a monopoly on all US launches (until the Challenger accident, when the EELV program started).
As no Shuttles were ever launched from the West coast, were there simply no polar orbiting satellites launched between 1981-1986?