In 1964, the American Research Bureau did  only TV measurement. It would be about a year before they launched radio ratings in Detroit, going national over the next years.

In the 70's, we would call the radio ratings "Arb's" but not before Arbitron gained agency acceptance and caused Hooper ("Hooperatings") and The Pulse to fall by the wayside as buying tools.

Of course, ARB has grown, and visitors no longer have to park on the grass.