They first dyed the Chicago River green for St. Patrick’s Day in 1962, after experiments with the dye in 1961.

Quick Scoop: How It Started

  • In 1961, Chicago plumbers were using a bright green tracing dye to find illegal sewage leaks in the river.
  • City leaders noticed how striking the color looked and decided to use it as part of St. Patrick’s Day festivities.
  • On March 17, 1962, they officially dyed the Chicago River green for the first time, kicking off the tradition we know today.

So if you’re wondering “when did they start dyeing the Chicago River green?” — the short, on-the-record answer is: St. Patrick’s Day 1962 , inspired by plumbing work in 1961.

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