The Chicago River was dyed green to celebrate St. Patrick’s Day, continuing a tradition that dates back more than 60 years.
Boats circulated on the river on Saturday to dump dye in the water.
The initiative of a union of Chicago plumbers, the Plumbers’ Union Local 130is one from 1961.
That year, union chief executive Stephen Bailey asked one of his plumbers why his overalls were green, a statement said.
He then realized that the dye used to detect leaks in the river had turned green.
It was then that he had the idea of using this dye to dye the river green on the occasion of St. Patrick’s Day, given that it was harmless to the environment, because already thought to discharge into bodies of water.
Since 1962, dye – the recipe for which remains secret – has been poured into the river every year by city plumbers.
The event coincides with the St. Patrick’s Day Parade in Chicago.
Just over 18 kilograms of dye are used to turn the river green.
See green water flowing through the middle of downtown Chicago in the video above