History Behind The Moscow Mule: Created in 1941 by Jack Morgan of the Cock N' Bull Tavern in Los Angeles and John G. Martin of the Hublein Company. John was introducing a Russian vodka to the United States and Jack had an overstock of ginger beer. The two created the cocktail and teamed up with a friend of Jack's who had recently purchased a copper factory. Photos of the celebrities who frequented the Cock N' Bull Tavern on Sunset Boulevard enjoying the drink helped fuel sales as everyone wanted "the drink in the copper mug!"
See Jeffrey Morgenthaler's ginger beer recipe here.