In the late 1970's in Cincinnati, the Cincinnati Association Of Broadcasters wanted to make the point that advertising on radio was more effective than any other medium.
So, they came up with the concept known as "Plummet Mall". A complete shopping mall to be constructed underground. Using the catchphrase, "the best deals in town are in a hole in the ground...Plummet Mall!"
The thing was...the mall...was fake!
Equal buys promoting the new "mall" were made on every major radio station in Cincinnati. And the commercials began.
Suddenly, the whole city was talking about "Plummet Mall". Everyone was talking about the concept, but no one knew exactly where the mall was being built!
The broadcasters realized they had made their point. So, on the final :60 spot, it was announced that, due to seismic shifts in the tectonic plate, Plummet Mall had been relocated to someplace like Kansas.
It proved radio's potential drawing power...because the whole city was talking about it. Even though, it was a 100% fake. It may not have had the biggest response of all, but still significant.