Good term!
And my point is that, until ARB rolled out its diary-based system in the latter part of the 60's, local market radio reports from Pulse and Hooper were based on the toll-free calling zone of the central city. It would be an interesting item of curiosity to know what that zone was in Buffalo in 1958.
Of course people use the main city of a market as an umbrella to cover sometimes unknown suburbs. For 30 years, when asked where I lived, I said "San Juan" even though I lived in Guaynabo, Caguas and Río Piedras for most of the time... but who has ever heard of those?
Yet the fact is that those ratings from the early days of Top 40 were based on a very tiny core market, and did not cover the suburbs and, of course, did not include adjacent counties. The Hooper model was developed back when C. E. Hooper worked for Starch decades before when cities were compact and phone calls outside the central area were relatively expensive.
I have a hard time thinking of any well done early Top 40 station anywhere in the US that was not an instant success. Some miserable signals, such as KOBY in San Francisco and WCPO in Cincinnati and WRIT in Milwaukee beat every other station in grand fashion. And the original Top 40 station, KOWH in Omaha, was a 500 watt daytimer and ended up with half the local audience.
Much of that success of poor signal stations had to do with the reticence of owners of big signals to go to Top 40 and the fact that the puny signals were, actually, great signals in the limited survey areas of ratings in the pre-ARB era.
Buth WBNY and WWOL lost due to the superior format execution of WKBW, not the signal. WBNY's signal was just as usable as WKBW's signal in the ratings survey area.
In the low-noise environment of the late 50's, that was possible. But the day signal was mostly limited to the immediate market.
Up until ARB came into Buffalo in the late 60's, the survey area was not even all of Erie County... based on the AT&T tariff data I could find, the Pulse dialing area did not include 70% of that county and non of Niagara County.
As important as those factors is the huge rise in man-made noise, which makes the use of even the most powerful AM stations a challenge.