The Chicago River dyeing is officially complete as St. Patrick's Day celebrations are underway in the city.
The iconic tradition turns the downtown Chicago waterway into a bright green, lasting for several days as several St. Patrick's Day events take place throughout the city.
While the dye lasts for several days, the bright color seen immediately after the dyeing begins to fade after a few hours.
The process of dyeing the river, however, takes around 45 minutes to one hour.
The full 2025 Chicago River dyeing can be seen in the player above.
Here's what else to know about the city's annual St. Patrick's Day tradition:
Local
When did the tradition begin?
The story began in 1961 when Stephen Bailey, the business manager of the Chicago Plumbers Local 130 union, was approached by a plumber whose overalls had been dyed a remarkably brilliant shade of green.
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According to the story, the dye used to detect leaks in the sewer system along the Chicago River turned the water green, and the idea was born to dye the river green in honor of St. Patrick’s Day.
Each year, the Journeyman Plumbers Local 130 heads out on boats onto the Chicago River and pours an orange concoction into the water. In a seeming blink of an eye, the dye turns from orange to green, and the water maintains that brilliant hue for the iconic holiday.
What's in the dye?
The answer to this has remained a mystery for years.
The plumbers union, Choose Chicago says, "still holds the river-dyeing honors today."
But you won't be able to find their recipe anywhere.
"Their environmentally friendly dye formula remains a closely kept secret," Choose Chicago says.
How do they dye it green?
Each year the Chicago Plumbers union uses boats along the Chicago River, using a concoction that sprays dye out of plumping pipes and spout pumps.
But the mysterious mixture doesn't come out green - it's actually orange.
However, once the dye sets in, the color changes to green.
According to Local 130, other cities have attempted similar feats, but never found success.
