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The Origin Behind Chicago’s Green River

400,000 people crowd around the Chicago River to see it transformed into a St. Patrick’s Day icon.

The temporary emerald green tinge has been a custom for years, but how did it start?

In 1962, the Mayor of Chicago, Richard J. Daley was attempting to bring people to the waterfront. At the time, the Chicago river was a “sewage-filled eyesore.” No one really hung out around the piece of water for long periods of time, but Daley was determined to change that. Attempting to reduce the pollution issue in the river, he wanted to pinpoint where the problem occurred the most. By working with a team of environmentalists, they poured special dye in the river to see what was being “discarded into the waterway and by whom.”

MarchforScienceCHI on Twitter

Chicago continues its Patty's day tradition. But did you know the Chicago River was first dyed green in 1962 by accident? #MFSChi #180yrSci



Stephen Bailey, a member of the Chicago Journeymen Plumbers, noticed green overalls from the members who poured the anti-pollution dye into the river. Bailey was inspired by the green tinge to the river and thought “why not dye the whole river green?”

ReginaWaldroupNBC5 on Twitter

The @Chicago River is going green for St. Patrick's Day. #StPatricksDay #greenriver #chicago #green


Months later, city officials tested out the idea. By pouring 100 pounds of a chemical into the water, the river turned green for an entire week. However, their original dye was not safe for the already polluted area.

YODER on Twitter

Dying of the Chicago river this morning


Their “oil-based fluorescein that many environmentalists warned was actually damaging the river even more.” So, they invented a new way to alter the Chicago river’s color; vegetable dye.


Believe it or not, the powder is actually orange before it hits the water. Unfortunately, the rest of the formula is kept secret by city officials. The entire transformation beings promptly at 9:15 am on the Saturday of the Chicago parade. It takes a team of six people, all of which are in boats, to pour the concoction into the water. With the help of flour sifters and boat motors, the river is magically transformed within forty-five minutes.


As compared to a week-long green color, these days, the dye stays for five hours. Regardless, it’s a great way to celebrate Irish heritage on the luckiest day on Earth!


Sarah Harley is a Hufflepuff living in the NYC area. When she is not talking to random animals or collecting stickers, she is a comedy writer working in television production. Tweet her at @lumpyspacederp