While a Margarita can be ordered skinny, spicy, or in the style of a Tommy’s Margarita, and a Daiquiri claims many iterations, asking for a Whiskey Sour begets, at most, one question: egg white or not?

But that’s not to say the Whiskey Sour has not been riffed upon. Through modifiers ranging from ginger syrup to red wine, the class of Whiskey Sours has taken on a life of its own. In the canon of modern classics alone, the drink has inspired several recipes. Most notably, it provided the blueprint for the Penicillin, a smoky-spicy variation, which quickly became an international sensation, leading some young bartenders to believe it had a much longer history than its relatively recent origins at Milk & Honey in 2004. (The Penicillin was itself a riff on the Gold Rush, a bourbon-based Whiskey Sour made with honey as the sweetener, from the same pioneering bar). Other modern classics have even evolved to more closely resemble the Whiskey Sour, such as Jeffrey Morgenthaler’s Amaretto Sour, which sees the addition of cask-proof bourbon in the oft-derided drink.

The Whiskey Sour has also been a template upon which bartenders have stamped their own regional or house embellishments. Both coasts have signature riffs: The Brown Derby, born in glitzy 1930s West Hollywood, shakes up bourbon with grapefruit juice and honey syrup, while the New York Sour, established in New York in the early 20th century, adds a float of red wine to the classic construction. There are signature Whiskey Sours from a host of lobby bars, too, like the 1930s-era Algonquin (from the New York hotel of the same name) made with pineapple juice, the more modern Two Dylans, made with orgeat at the newly renovated Hotel Chelsea, and the Up in Smoke, made with amaro at the Freehand Hotel in Miami.

Though the drink has been circulating since around the 1860s, experimentation with the template shows no signs of stopping. The classic has been turned “rich and soulful” thanks to a measure of PX sherry in Jeremy Oertel’s Betty Carter, and has been kicked up with spice in Natasha David’s peachy Mountain Man. The drink has even taken on an aperitif bent, balancing the richer elements of the cocktail with citrus and herbs in Andrew King’s The Thirsty Monk, designed to be consumed before a meal.

Perhaps it’s the cocktail’s ability to shift seamlessly through drinking eras that has allowed it to persist for so long. Or perhaps, it’s the drink’s inherent riffability, underlying countless modern cocktails, that has kept it alive. As Dan Sabo, who created our favorite (albeit unorthodox) recipe for the classic, says of the Whiskey Sour: “There are all kinds of ways to hack this and bring it into the future. It’s endlessly editable.”