>>> When did they deliver AC at 25 cycles? I do recall some 50 cycle
>>> companies around that had to change after the end of WWII.
>> I don't know when the last 25-cycle power was phased out. Keokuk, Iowa,
>> had a 25-cycle hydroelectric plant -- driven by the Mississippi River,
> Doesn't Amtrak still have some 25 Hz power plants from its predecessor
> lines in the Northeast Corridor? Some locations have been converted
> to commercial power, some of them still owned and operated by Amtrak
> still provide 25 Hz.
Correct And there are some other private installations using 25-cycle as well.
I was referring to _public_ power distribution at 25-cycle. Where that was what you found at the outlet in your house, or office.
Reasonably common through the 1930s, at least. Best data I can find, so far, *seems* to put end of public 25-cycle distribution somewhere post-WWII to mid-1950s.