A dear friend recently sent me two solid copper Moscow Mule mugs. Trust me when I tell you that these copper mugs get COLD.
The cocktail was invented in 1941 by John G. Martin of G.F. Heublein Brothers, Inc., an American East Coast spirits and food distributor based in Hartford, Connecticut, and "Jack" Morgan, President of Cock 'n' Bull Products (which produced ginger beer) and proprietor of the Cocks 'n' Bulls restaurant on Sunset Boulevard in Los Angeles which was popular with celebrities.
The Moscow mule is almost always served in a copper mug. The popularity of this drinking vessel is attributable to Martin, who went around the country to sell Smirnoff vodka and popularize the Moscow mule. Martin asked bartenders to pose with a specialty copper mug and a bottle of Smirnoff vodka, and photographed a Polaroid picture of them. He took two photos, leaving one with the bartender for display. The other photo would be put into a collection and used as proof to the next bar Martin visited of the popularity of the Moscow mule. The copper mug remains, to this day, a popular serving vessel for the Moscow mule, primarily due to tradition and aesthetic reasons.
Here's the recipe for the Classic Moscow Mule
Fill a copper mug halfway with ice. Add 2 oz. quality vodka, juice of half a lime and top with 4 oz. Ginger Beer.
Garnish with a lime slice and/or mint leaves and serve.