Every year about this time, Chicago decides that blue-brown rivers are boring. So the local plumber’s union uses a top secret combination of what they pinky-swear are ecologically-safe chemicals to dye the river green. Very very green.
Chicago has been dying its river since the early 1960s
The practice dates back to 1962, when Mayor Richard J. Daley and his boyhood friend Stephen M. Bailey decided it would be a bit of a lark to dye the river green as part of the city’s St. Patrick’s Day parade. The city has dyed its river on the day of the parade ever since.
How does Chicago dye an entire river?
According to this how-to from the Chicago Tribune, six members of the local plumbers union pile into two boats on the morning of the St. Patrick’s Day parade to spread the chemicals down the river (four crew members in the large boat, and two in a smaller one).
The dye job begins at 9:15 a.m. sharp under the Michigan Avenue bridge near Wacker Drive. Three of the crew in the large boat use kitchen sifters to sprinkle the top-secret powder on the river, while the fourth drives the boat downriver.
Meanwhile, the two folks in the smaller boat drive wackily through the powder trail to disperse the chemicals through the water to turn the river a more uniform green. (Sounds fun, doesn’t it?)
The entire process takes about 45 minutes. If you missed the display Saturday morning, you can watch a time-lapse video of it here.
How long does the dye job last?
This photo was taken on Saturday afternoon, about six hours after the river was dyed. I’m told the dye job lasts about three days. I can’t promise that The Seven-Year-Old and I will make it to downtown today to check, but if we do, we’ll report back.
Fun fact: The top-secret powder they use to dye the river is orange, not green.
I honestly can’t decide whether I want to know the chemistry behind that. Do they test the river for pollutants before dying and adjust the formula every year to compensate, or is it a more straightforward manipulation of light and color?
Regardless, Happy St. Patrick’s Day!
- What it looks like in time lapse when Chicago dyes its river green (MarketWatch)
- How the Chicago River is dyed green (Chicago Tribune)