The annual tradition of dyeing the Chicago River green began on March 14 as part of the city’s St. Patrick’s Day celebrations. Members of Journeymen Plumbers Local Union 130 started pouring their signature blend of vegetable-based dyes into the river at 9:52 a.m., transforming the water between Columbus Drive and Orleans Street into a bright green spectacle.
This marks the 64th year that the local plumbers union has led this event, which draws thousands of spectators to downtown Chicago each year. People lined both sides of the river early Saturday morning to witness the process, which has become a well-known symbol of Chicago and is frequently featured in television shows, movies, and social media posts.
The tradition dates back to 1962 when Stephen Bailey, then business manager for the union, suggested using dye—originally intended for tracing leaks in buildings—as a festive way to honor St. Patrick’s Day. The formula remains secret but is known to be vegetable-based and environmentally friendly. Only about 40 pounds of powdered dye are needed each year, spread from motorboats and shot into the river by hoses aboard Architecture Tours boats while other vessels help mix it evenly throughout the water.
The effect lasts several days and continues to attract large crowds who come dressed in festive attire, with many taking photos or recording videos as they celebrate along Wacker Drive and nearby bridges. The event also sees increased police presence managing crowds and ensuring safety during festivities.
As revelers enjoy this unique display, organizers maintain that keeping the exact recipe confidential helps preserve both tradition and excitement around one of Chicago’s most recognizable holiday events.
