Chicago Dyes River Green for St. Patrick's Day

Decades-old tradition started by plumbers and the mayor in the 1960s

Mar. 13, 2026 at 9:38pm

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Chicago has been dyeing its river green ahead of St. Patrick's Day for decades, a tradition that started in the 1960s when a group of plumbers accidentally discovered an orange dye that turned the water emerald green. The head of the local plumbers union then called his friend, the mayor at the time, and they hatched a plan to use the dye to color the Chicago River for the annual St. Patrick's Day celebration.

Why it matters

Dyeing the Chicago River green has become one of the city's most beloved traditions, drawing thousands of spectators each year to witness the transformation. The annual event is a celebration of Chicago's Irish heritage and a way to kick off the St. Patrick's Day festivities in style.

The details

In the 1960s, a group of Chicago plumbers were searching for a leak using an orange dye, which ended up bubbling up emerald green when it hit the water. The head of the Local Plumbers Union 130 then called his best friend, who happened to be the mayor at the time, Richard J. Daley, and they decided to use the dye to color the Chicago River ahead of St. Patrick's Day. While they initially wanted to dye Lake Michigan, they settled on the river as a more manageable task.

  • The river will be dyed starting at 10 a.m. on March 14, 2026.

The players

Local Plumbers Union 130

The local plumbers union that discovered the orange dye that turned the Chicago River green.

Richard J. Daley

The mayor of Chicago at the time who worked with the plumbers union to establish the tradition of dyeing the river green for St. Patrick's Day.

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What’s next

NBC Chicago will offer a live feed of the river dyeing event, streaming it online for viewers to watch.

The takeaway

The annual dyeing of the Chicago River has become a beloved tradition that celebrates the city's Irish heritage and kicks off the St. Patrick's Day festivities in style. The tradition started by chance in the 1960s when a group of plumbers discovered a dye that turned the water green, and it has endured for decades as one of Chicago's most iconic events.