The Pan-American Exposition was a World’s Fair held in Buffalo, New York in 1901. Buffalo was one of the largest American cities at the time and was chosen as a World’s Fair site in part due to its proximity to major railways. The Exposition showcased many exhibits, most notably the use of electricity. Hydroelectric power generated by the Niagara River powered the Exposition grounds and buildings. President William McKinley was assassinated while attending the Exposition.