The Chicago river is colored a bright green today, in celebration of St. Patrick's Day!
But how do they manage to pull off such a feat?!
The tradition goes back to 1962, when Chicago Mayor Richard J. Daley -- a descendant of Irish immigrants -- had the idea of turning Lake Michigan green. While the lake was far too big, a group of plumbers figured out a way to color the city's river using 100 pounds of green dye.
That dye ended up keeping the water green for weeks... so nowadays they use a vegetable-based powder dye that wears off after a few days!
"The dying of the river green is such a public event that it helped concretize the celebration of St. Patrick's day in the city," Peter Alter, chief historian at the Chicago History Museum said.