Also, there was the "War of the Currents" (Edison's DC system vs. Tesla's AC), and even when AC won out, a variety of frequencies were used. Even though 60 Hz d

Also, there was the "War of the Currents" (Edison's DC system vs. Tesla's AC), and even when AC won out, a variety of frequencies were used. Even though 60 Hz dominated in North America and became the standard, there was once a 50 Hz grid in southern California, and a 25 Hz grid in southern Ontario and western New York. Vestiges of the 25 Hz system remained in service as late as 2006. https://ethw.org/Early_Electrification_of_Buffalo https://ethw.org/Early_Electrification_of_Buffalo