Savage said:
Upstate New York is the location of many of the country's oldest licensed FM facilities which were authorized before the formal FCC allocation tables were adopted in the early 50s. (In fact, 98.9 in Rochester is the country's first licensed commercial FM, dating to 1939, when it went on the air as Stromberg-Carlson's FM sister to WHAM. WHFM of course operated in the old low-frequency band before the postwar move to 98.9.)
1964, for the current FM rules.
(how sure are you about WHFM being the first commercial FM? WSM-FM makes a pretty solid claim on that. Or is it that WSM was authorized first but WHFM got the license-to-cover first? Or are you only counting FMs that are still on the air? - as WSM shut theirs down in the early 1950s, the WSM-FM that exists today only dates to the early 1960s)
_________________________________________________
Through much of the 1950s and until 1964,
there was no limit to the amount of power an FM station could run.. I mean, you had to obey the figure on your license; the equipment necessary to operate at the requested power had to exist; and you couldn't interfere with other stations, but when you filed that application you could ask for as much power as you wanted and it would be granted. What I
suspect was going on was that the FCC felt the FM service was slow in rolling out, and by authorizing very high-powered stations, they could provide FM service to outlying areas where nobody local was interested in FM.
In 1964, the framework of the current FM rules was adopted. This established the current table of allocations, and the absolute limit of 50kw/500' (later 150m) in the East. They "grandfathered" any station that was already authorized to operate at powers greater than what was in the new rules. (but it should be noted those stations are not protected from interference in the areas where their "extra" coverage happens. 102.5, for example, may be operating at 110kw/355m, but it's protected as if it was running 50kw/150m.)
There were actually quite a few "superpower" FMs authorized in the late 1940s and early 1950s. Powers of 200-300-400kw were not particularly unusual. But also in the early 1950s, it became apparent there was no money in FM. Many of these superpower FMs were never built, or got their permits modified for much lower powers. Others actually did go on the air, but by the mid/late 1950s had shut down & surrendered their licenses. So by 1964, there weren't that many superpower FMs left to grandfather.