The Boulevardier is a variant of the cocktail known as the Negroni, which is simply a ginned-up version of an Americano. This is what Americans living in Italy used to call it when they added sparkling water to a Milano-Torino, the classic aperitivo of the day that paired bitter Campari from Milano, with sweet Martini & Rossi vermouth from Torino.
The Negroni was invented by an Italian count who decided to reanimate the watered down drink by nixing the fizz and adding gin to the mix.
When the American expat publisher of a Parisian literary magazine called the The Boulevardier opted to use Bourbon in his Negroni instead of gin, the following cocktail was born. Interestingly, Bourbon helps revive some of the intriguing woodsy herbal notes found in the original Milano-Torino that were subsequently diluted by first seltzer, and then gin.
1 1/2 oz. bourbon
1 oz. Campari
1 oz. sweet vermouth
*In French, a Boulevardier is someone seen on the fashionable boulevards. A “man about town”, so to speak.