In the United States especially, St. Patrick’s Day means green—green clothes (lest you get pinched), green décor and, of course, green beer. In this day and age, all it takes to make a brew as emerald as the Isle herself is a couple drops of green food coloring. But a century ago, when the practice first started, drinkers got the hue from something much less palatable—and a little poisonous: an iron-based laundry whitener referred to as “wash blue.”
Most sources say that the idea for the hued brew was cooked up in New York City 101 years ago. (That’s right—green beer began as a purely American tradition.) That year, as Don Russell over at Philly.com writes, the toastmaster of a Bronx social club’s St. Paddy’s celebration was a coroner named Dr. Thomas Hayes Curtin. To the surprise and delight of party-goers, the event’s big dinner and sing-along was accompanied by Dr. Curtin’s own recipe for a festive draft. Of the event, one newspaper from the time reported:
Everything possible was green or decorated with that color and all through the banquet Irish songs were sung and green beer was served. No, it wasn’t a green glass, but real beer in regular colorless glass, but the amber hue was gone from the brew and a deep green was there instead. [. . .] All the doctor would tell inquisitive people was that the effect is brought about by one drop of wash blue in a certain quantity of the beer.
“Wash blue” is an iron powder solution embedded with a dye and was once used to make dingy whites bright again. Combined with lager—presumably at a potency level low enough not to cause any non-booze related illnesses—it apparently made for a delightfully festive draft.
But, as Vox’s Phil Edward points out, the world may have been introduced to green beer even before Curtin’s concoction hit the scene. A 1910 edition of the Spokane Press announced beneath the headline “GREEN BEER BE JABBERS!” that there was “at least one bar in town today that is reminding the thirsty that it is the Sivententh of March, God Rist His Sowl.” (“Be Jabbers,” Edwards reports, was an “excited swear.”) No word on how that Washington barman dyed his drink.
By the 1950s green beer became a holiday staple. Today, it makes up some of the around 4.2 billion pints of brew consumed in celebration of St. Patrick’s Day.
And while we’re on the subject of dying liquid green—which city was the first to start the practice of coloring a large body of water emerald in honor of St. Patrick’s Day? That honor is disputed, but appears to go to Savannah, Georgia, which first attempted to dye the city's river in 1961. The color only lasted for about 10 minutes in the swiftly moving water—but the next year, officials from Chicago are said to have consulted the mastermind of that stunt to figure out how to color their own river. Ever since 1962, the Chicago River has run green in honor of the holiday, with the city eventually perfecting the process and becoming the best-known locale for the phenomenon.