Didn’t get a chance to visit Chicago this weekend and see the city’s St. Patrick’s Day tradition? Well, fear not! Thanks to a bird’s eye view time lapse video, you get to feast your eyes on the Chicago River being dyed a holiday-appropriate bright green!

For the uninitiated, this tradition started over 50 years ago by a Plumbers Union that noticed a dye they used to detect leaks in sewage pipes turned bright green when introduced to the river. Fluorescein, which some may recognize as the go-to water rescue fluorescent tracer from your World War IIs to your NASA splash downs, was used for a few years until deemed too dangerous by the EPA. Who on earth would have thought pouring hundreds of pounds of dangerous chemicals into a municipal waterway could ever be considered hazardous? Hey, it was the ’60s… we’re lucky they weren’t using anything radioactive.

In 1966, a safer vegetable dye substitute was introduced in order to protect Chicago’s river wildlife, which, if you’ve ever seen the Chicago river, must be either still hiding or have headed down to Springfield IL.

Years ago a whopping 100 pounds of dye was used turning the waters of downtown Chicago a striking Kelly green for up to a week. Nowadays, the very same Plumbers Union that began the tradition spread about 40 pounds of the dye on the weekend closest to St Patrick’s Day which still greens up the river, but for only a few hours until it dissipates. Drawing thousands of green-clad tourists and locals, onlookers of this Chicago tradition consider it the starting point in what is arguably one of the better (read: rowdy) St. Paddy’s Day weekends this side of Ireland.

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Does your city have a St. Patrick’s Day tradition? Did I miss a chance to make a Hulk blood joke?  Know where I can get a really great corned beef reuben year-round in Chicago? Let me know on Twitter (@TheBlakeRodgers) or let us know in the comments.