CHICAGO (CNN NEWSOURCE) - For the past 56 years, the Chicago River is running green in honor of Saint Patrick's Day.
The streaks of neon green come from two boats operated by the descendants of two Chicago police officers, originally tasked with turning the water green in 1962.
The mayor originally wanted to turn all of Lake Michigan green but it was just too big.
As for exactly how the process works, well, that's a closely guarded secret.
The men who know the recipe will only say the orange powder called "leprechaun dust" -- which turns green when it hits the water -- does not harm the environment.
They have only changed the river another color once. In 2016, they dyed the water blue in honor of the Chicago Cubs World Series victory.
Other cities that dye bodies of water green for Saint Paddy's Day include Savannah, Georgia and Tampa, Florida.
Even the White House gets in on the fun by turning the water in the fountain outside the White House shamrock green.
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