Which historical event served as a massive public demonstration confirming the superiority of AC power transmission?

Answer

The 1893 World's Columbian Exposition in Chicago.

Westinghouse won the contract to illuminate the 1893 World's Columbian Exposition using AC power, which served as a large-scale, highly visible proof of concept for the technology over the older DC standard.

Which historical event served as a massive public demonstration confirming the superiority of AC power transmission?
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