I never heard, nor am clear on what was going on in relation to super-big station(s) in the 1960s. From what I understand Wolfman Jack, and others, would broadcast from Mexico ( Mexico city? ) with a monsterous amount of power, and at night much of the continental U.S. could hear it. I've heard of the power being as high at 250,000 watts, but whether that was true or not, I don't know. Some have said the stations were pumping so much power that it was actually dangerous. Any truth to that? When/why did it all start and when/why did it end. I would think that the U.S. wasn't thrilled with this/these station(s). If this would be better to move to the engineering board, I think that would be good.
The idea was for the Mexican stations, which are not governed by U.S. power regulations, to blast a BIG signal as far as possible. U.S. AM stations at that time were limited to 50K watts but no such limitation existed on the other side of the border.
Wolfman's transmitter sites were within a few miles of the US-Mexican border (not anywhere near Mexico City) as the programming was primarily intended for the U.S. market.
As for the power being dangerous, you'd have to ask an engineer with medical background but I doubt people were actually living/working right next to the antenna farm. We have TV stations here in Phoenix pumping out 100,000 watts which are within a mile or so of homes. Aside from the occasional report of someone hearing the 5 o'clock news coming from their fillings
I'm not aware of any "dangerous" side effects.