TD-40:
Good question. The answer varies depending on where you are. There was regional awareness of the stories long before there was national awareness. In some areas ... Nor Cal / SW Oregon, for instance ... based on newspaper reports, there have been stories as long as there have been European-descended people with printing presses. And of course there are the oral traditions of native people. So, how to say this right? I think this is something that was already here "waiting", not something we created upon our arrival.
My suspicion, regarding national consciousness, is it stems from Hollywood. Being somewhat adjacent to the Nor Cal area, picking newspaper articles and maybe even recreating in the areas along the Klamath tributaries, Hollywood saw BF as a new twist to slip into film, both big screen and TV (Six Million Dollar man, etc). That, in turn, pushed it into national consciousness whether accepted or just seen as a component of myth. It has snowballed from there.
++++
Regarding Ray Wallace ... apparently guilty of hoaxing, but definitely busted claiming credit for hoaxes he could not have perpetrated. I doubt we can ever be certain what his impact truly was.
edit to add: When it comes to Ray Wallace, I can't embrace him "admitting" to hoaxing, I have to qualify it by saying "claiming" to have hoaxed. Maybe that says what little confidence I have in ANYTHING he said ... even his confession is suspect.
MIB