The story of why parts of the US used 25 Hertz power instead of the standard 60 Hertz is interesting. Hydroelectric power was developed at Niagara Falls startin

The story of why parts of the US used 25 Hertz power instead of the standard 60 Hertz is interesting. Hydroelectric power was developed at Niagara Falls starting in 1886. To transmit power to Buffalo, Edison advocated DC, while Westinghouse pushed for polyphase AC. The plan in 1891 was to use DC for local distribution and (incredibly) compressed air to transmit power 20 miles to Buffalo, NY. By 1893, the power company decided to use AC, but used 25 Hertz due to the mechanical design of the turbines and various compromises. In 1919, more than two thirds of power generation in New York was 25 Hertz and it wasn't until as late as 1952 that Buffalo used more 60 Hertz power than 25 Hertz power. The last 25 Hertz generator at Niagara Falls was shut down in 2006. Details: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948 http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=4412948