I'm afraid what you read is totally incorrect.

Here in the U.K. we had old DC supplies in some areas which were still in use into the 1960s, at which time they were converted to AC.

I don't know the details of the conversion of old systems in America, but I would guess the 1960s is more likely the time when the last remaining DC sevices were changed to AC, as here.

P.S. On both sides of the Atlantic, many AC systems were installed way back in the 1890s. There was a long battle at the time between Thomas Edison (DC) and George Westinghouse (AC).

[This message has been edited by pauluk (edited 11-30-2001).]