I love this drink and greats have already written about it so I will be brief (My favorite article on it is this one . . ): The Boulevardier that is known and loved in the US was first found in print in the 1927 Barflies and Cocktails by Harry McElhone.
Its simple recipe hides layer after layer of complexity:
2 Oz Cyrus Noble Bourbon
1 Oz Campari
1Oz Sweet Vermouth
Build in a rocks glass and then add ice--stir until incorporated / chilled . . . or
Stir until chilled on ice and strain into a chilled cocktail glass.
Garnish with an Orange twist or a cherry.
Super easy, super delicious.
So the reason I decided to share this recipe is that, for some reason bartenders still do not know it. The last two times I asked for it the bartender said: " Oh, you mean a 'Whiskey Negroni' . . ."
Wow . . . The origins of the Negroni are fixed somewhere around 1920 in Florence. The Boulevardier was popular enough to have been included in an earlier cocktail manual by Harry (Harrys ABC of Mixing Cocktails) and was originated in Paris, apparently by a local socialite ( Edward Erskine Gwynne, Jr.) who publish a magazine called . . You guessed it Boulevardier.
Not only are the creations of these drink so historically close and regionally disparate--THE BASE SPIRIT IS COMPLETELY DIFFERENT.
So, anyways, lets all enjoy a Boulevardier.