Maybe D.C.’s favorite cocktail (favorite, at least, according to WCP’s latest research) won’t surprise you. The District has the highest percentage of heavy drinkers according to a new Detox study, so it fits that the cocktail poured most often in local bars is a boozy one.

Of more than 40 bars surveyed in D.C. proper, 39 percent said the Old Fashioned is the most popular drink they serve. The cocktail consists of brown booze (whiskey, bourbon, or rye) with sugar and bitters.

“Year-to-date, we have served 12,500 Old Fashioneds,” says Jack Rose Dining Saloon general manager Melody Stone. She says that’s about the same number as vodka & sodas, gin & tonics, whiskey & gingers, and rum & cokes combined.

Similarly, Glendon Hartley of Service Bar DC says, “We sell by far more $7 Old Fashioneds than anything else—it usually ends up being about double compared to the next highest selling drink.”

Across town, Parker Girard of Barrel says, “We’re on pace to sell about 8,500 Old Fashioneds this year, which is ridiculous. Milk Punch is a close second, but considering we don’t even have Old Fashioneds on the cocktail menu, that’s a pretty high number.” He continues to say that Manhattans and other drinks aren’t even close. “For reference, we’ve sold 200 margaritas this year. I couldn’t be prouder of our customers.”

George Sault of Black Jack and Tilt has a theory on why the drink is so in demand. “With just a little bit of added sugar, bitters, and dilution from stirring, the Old Fashioned is a great way to enjoy a whiskey without ruining the integrity of the spirit. Most people are drinking rye over bourbon in their Old Fashioned [these days].”

The Moscow Mule, which is made with a base of vodka, ginger beer, and lime, came in second at 17 percent.

“There is one drink on our list there that has sold 80 percent more than second place—The Blue Mule,” says John Kelly from Stoney’s on L Street NW. Stoney’s take on the Moscow Mule includes blueberry syrup, lime juice, ginger beer, “and of course our old friend vodka,” says Kelly.

Finally, the humble vodka & soda took third at 7 percent. “Our most-sold cocktail throughout the weekends is for sure a simple classic vodka soda,” says Thomas Honeycutt of Nellie’s Sports Bar. “Living in D.C., the pressure to stay fit and hit the gym, yet go out and live the social life is competitive.”

Bottoms up.