You may have stumbled upon some ephemera from the infamous War of the Currents : Thomas Edison/Niagra Power and Nikola Tesla/Westinghouse duking it out over whether DC or AC was safer!

In 1903, Edison electrocuted Topsy the Elephant at Coney Island, attempting to frighten people away from Tesla's alternating current. The Current War even spurred the invention of the electric chair.

Here's a decent brief explanation from Physics World: https://physicsworld.com/a/tesla-versus-edison-lessons-from-the-ac-dc-war/

There's even a 2017 movie about it, called The Current War. It's a dramatization and not necessarily reliable as far as historical accuracy, but fun nonetheless.