We are the #1 city for St. Patrick’s Day! And a lot of it has to do with this very cool tradition.

The tradition happened accidentally when a plumber from the Chicago Journeyman Plumbers Local used green dye to find the surce of the pollution of the Chicago River back in 1961.

Now three guys from Plumbers Local 130 use flour sifters to put 40 pounds of a top secret (environmentally friendly) orange powder to turn the river green every year. The fourth guy drives the boat.

If you want to see, it happens tomorrow morning at 9am and people line up along Wacker Drive.