CHICAGO -- It's an annual tradition in Chicago: Dyeing the Chicago River green for St. Patrick's Day.
Thanks to an awesome time-lapse video courtesy WGN, you can see it happen in a whole new way!
From the YouTube description: The annual tradition of Chicago River Dyeing Green for St. Patrick’s Day Celebration. Time lapses shot from Sheraton Grand Chicago and thanks to management. Location provides beautiful views along a river and Chicago Skyline.