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Photo by Tim Boyle/Getty Images
Photo by Tim Boyle/Getty Images

What Do They Use to Dye the Chicago River Green?

Photo by Tim Boyle/Getty Images
Photo by Tim Boyle/Getty Images

It wouldn’t be a St. Patrick’s Day celebration in the Windy City without 400,000 spectators crowding the banks of the Chicago River to “ooh” and “aah” at its (temporarily) emerald green tinge. But what do they use to dye the waterway?

First, a bit of history: The dyeing tradition became an annual thing more than half a century ago, in 1962, but its real origins go back even further. In the early days of his administration as Mayor of Chicago, Richard J. Daley was a man on a mission to develop the city’s riverfront area. There was just one problem: The river itself was a sewage-filled eyesore. In order to get to the bottom of the city’s pollution problem and pinpoint the exact places where waste was being discarded into the waterway (and by whom), Daley authorized the pouring of a special green dye into the river that would allow them to see exactly where dumping was occurring.

Fast-forward to late 1961 when Stephen Bailey—part of the Chicago Journeymen Plumbers Local, the city’s St. Patrick’s Day Parade chairman, and a childhood friend of Daley’s—witnessed a colleague’s green-soaked coveralls following a day of pouring Daley’s dye into the Chicago River. That gave Bailey an idea: If they could streak the Chicago River green, why not turn it all green?

Three months later, revelers got their first look at an Ecto Cooler-colored river when the city poured 100 pounds of the chemical into the water. They got a really good look, too, as the river remained green for an entire week.

Over the next several years, the same practice was repeated, and again it was carried out by the Plumbers Local. The only difference was that the amount of dye used was cut in half over the next two years until they finally arrived at the magic number: 25 pounds of dye = one day of green water.

Unfortunately, the dye that was intended to help spot pollution was an oil-based fluorescein that many environmentalists warned was actually damaging the river even more. After fierce lobbying, eco-minded heads prevailed and in 1966 the parade organizers began using a powdered, vegetable-based dye.

While the exact formula for the orange powder (yes, it's orange until it's mixed with water) is kept top-secret—in 2003 one of the parade organizers told a reporter that revealing the formula would be akin to “telling where the leprechaun hides its gold”—there are plenty of details that the committee lets even non-leprechauns in on:

The dyeing process begins at 9:15 a.m. on the morning of the parade (which is always held on a Saturday) when six members of the local Plumbers Union hop aboard two boats, four of them on the larger vessel, the remaining two on a smaller boat.

The larger boat heads out onto the water first, with three members of the crew using flour sifters to spread the dye into the river. The smaller boat follows closely behind in order to help disperse the substance.

Approximately 45 minutes later, voila, the Chicago River is green! But don’t expect it to stay that way. These days, the color only sticks around for about five hours. Which is roughly the same amount of time it takes to get a perfectly poured pint of Guinness if you venture out to an Irish pub on St. Patrick’s Day.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This post originally appeared in 2015.

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Big Questions
Where Should You Place the Apostrophe in President's Day?
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Happy Presidents’ Day! Or is it President’s Day? Or Presidents Day? What you call the national holiday depends on where you are, who you’re honoring, and how you think we’re celebrating.

Saying "President’s Day" infers that the day belongs to a singular president, such as George Washington or Abraham Lincoln, whose birthdays are the basis for the holiday. On the other hand, referring to it as "Presidents’ Day" means that the day belongs to all of the presidents—that it’s their day collectively. Finally, calling the day "Presidents Day"—plural with no apostrophe—would indicate that we’re honoring all POTUSes past and present (yes, even Andrew Johnson), but that no one president actually owns the day.

You would think that in the nearly 140 years since "Washington’s Birthday" was declared a holiday in 1879, someone would have officially declared a way to spell the day. But in fact, even the White House itself hasn’t chosen a single variation for its style guide. They spelled it “President’s Day” here and “Presidents’ Day” here.


Wikimedia Commons // Public Domain

Maybe that indecision comes from the fact that Presidents Day isn’t even a federal holiday. The federal holiday is technically still called “Washington’s Birthday,” and states can choose to call it whatever they want. Some states, like Iowa, don’t officially acknowledge the day at all. And the location of the punctuation mark is a moot point when individual states choose to call it something else entirely, like “George Washington’s Birthday and Daisy Gatson Bates Day” in Arkansas, or “Birthdays of George Washington/Thomas Jefferson” in Alabama. (Alabama loves to split birthday celebrations, by the way; the third Monday in January celebrates both Martin Luther King, Jr., and Robert E. Lee.)

You can look to official grammar sources to declare the right way, but even they don’t agree. The AP Stylebook prefers “Presidents Day,” while Chicago Style uses “Presidents’ Day.”

The bottom line: There’s no rhyme or reason to any of it. Go with what feels right. And even then, if you’re in one of those states that has chosen to spell it “President’s Day”—Washington, for example—and you use one of the grammar book stylings instead, you’re still technically wrong.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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holidays
10 Things You Might Not Know About Chinese New Year
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Some celebrants call it the Spring Festival, a stretch of time that signals the progression of the lunisolar Chinese calendar; others know it as the Chinese New Year. For a 15-day period beginning February 16, China will welcome the Year of the Dog, one of 12 animals in the Chinese zodiac table.

Sound unfamiliar? No need to worry: Check out 10 facts about how one-sixth of the world's total population rings in the new year.

1. THE HOLIDAY WAS ORIGINALLY MEANT TO SCARE OFF A MONSTER.

Nian at Chinese New Year
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As legend would have it, many of the trademarks of the Chinese New Year are rooted in an ancient fear of Nian, a ferocious monster who would wait until the first day of the year to terrorize villagers. Acting on the advice of a wise old sage, the townspeople used loud noises from drums, fireworks, and the color red to scare him off—all remain components of the celebration today.

2. A LOT OF FAMILIES USE IT AS MOTIVATION TO CLEAN THE HOUSE.

woman ready to clean a home
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While the methods of honoring the Chinese New Year have varied over the years, it originally began as an opportunity for households to cleanse their quarters of "huiqi," or the breaths of those that lingered in the area. Families performed meticulous cleaning rituals to honor deities that they believed would pay them visits. The holiday is still used as a time to get cleaning supplies out, although the work is supposed to be done before it officially begins.

3. IT WILL PROMPT BILLIONS OF TRIPS.

Man waiting for a train.
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Because the Chinese New Year places emphasis on family ties, hundreds of millions of people will use the Lunar period to make the trip home. Accounting for cars, trains, planes, and other methods of transport, the holiday is estimated to prompt nearly three billion trips over the 15-day timeframe.

4. IT INVOLVES A LOT OF SUPERSTITIONS.

Colorful pills and medications
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While not all revelers subscribe to embedded beliefs about what not to do during the Chinese New Year, others try their best to observe some very particular prohibitions. Visiting a hospital or taking medicine is believed to invite ill health; lending or borrowing money will promote debt; crying children can bring about bad luck.

5. SOME PEOPLE RENT BOYFRIENDS OR GIRLFRIENDS TO SOOTHE PARENTS.

Young Asian couple smiling
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In China, it's sometimes frowned upon to remain single as you enter your thirties. When singles return home to visit their parents, some will opt to hire a person to pose as their significant other in order to make it appear like they're in a relationship and avoid parental scolding. Rent-a-boyfriends or girlfriends can get an average of $145 a day.

6. RED ENVELOPES ARE EVERYWHERE.

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An often-observed tradition during Spring Festival is to give gifts of red envelopes containing money. (The color red symbolizes energy and fortune.) New bills are expected; old, wrinkled cash is a sign of laziness. People sometimes walk around with cash-stuffed envelopes in case they run into someone they need to give a gift to. If someone offers you an envelope, it's best to accept it with both hands and open it in private.

7. IT CAN CREATE RECORD LEVELS OF SMOG.

fireworks over Beijing's Forbidden City
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Fireworks are a staple of Spring Festival in China, but there's more danger associated with the tradition than explosive mishaps. Cities like Beijing can experience a 15-fold increase in particulate pollution. In 2016, Shanghai banned the lighting of fireworks within the metropolitan area.

8. BLACK CLOTHES ARE A BAD OMEN.

toddler dressed up for Chinese New Year
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So are white clothes. In China, both black and white apparel is traditionally associated with mourning and are to be avoided during the Lunar month. The red, colorful clothes favored for the holiday symbolize good fortune.

9. IT LEADS TO PLANES BEING STUFFED FULL OF CHERRIES.

Bowl of cherries
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Cherries are such a popular food during the Festival that suppliers need to go to extremes in order to meet demand—last year Singapore Airlines flew four chartered jets to Southeast and North Asian areas. More than 300 tons were being delivered in time for the festivities.

10. PANDA EXPRESS IS HOPING IT'LL CATCH ON IN THE STATES.

Box of takeout Chinese food from Panda Express
domandtrey, Flickr // CC BY-NC 2.0

Although their Chinese food menu runs more along the lines of Americanized fare, the franchise Panda Express is still hoping the U.S. will get more involved in the festival. The chain is promoting the holiday in its locations by running ad spots and giving away a red envelope containing a gift: a coupon for free food. Aside from a boost in business, Panda Express hopes to raise awareness about the popular holiday in North America.

A version of this story originally ran in 2017.

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