much of it related to Niagara Falls and other power
systems
modeled after it.
The IIRC oldest US generating station still in operation (on original hardware anyway) is
at Mechanicville, NY. It is hydroelectric and originally fed 40 Hz AC to Schenectady. They
just sped up the alternators when they connect it to the 60 Hz grid!
I hear the European equivalent of US 25 Hz traction power is 16.6 Hz.
Thanks,
Jonathan