How Do They Dye the Chicago River Green for St. Patrick's Day?

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iStock

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 how do officials turn the water green?

First, a bit of history: The dyeing tradition became an annual thing nearly 60 years 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 will begin at 9 a.m. on the morning of the parade, Saturday, March 17 (it's 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. (The best place to catch a glimpse is from the east side of the bridge at Michigan Avenue, or on Upper and Lower Wacker Drive between Columbus and Lake Shore Drives.)

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.

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What Causes Red Tides?

William West/AFP/Getty Images
William West/AFP/Getty Images

Every once in a while, the ocean turns the color of blood and scores of dead fish rise to the surface. The phenomenon might look like a biblical plague, but the source is far more mundane. It's just algae.

Red tides occur when there’s a sudden population boom among specific kinds of algae, which in enormous quantities become visible to the naked eye. They occur all over the world. In the Gulf of Mexico, the culprit behind red tides washing onto coastlines from Texas to Florida is usually a type of microscopic algae called Karenia brevis. It produces toxic chemicals that can cause symptoms ranging from sneezing and eye irritation to disorientation, vomiting, and breathing difficulties. It's often fatal for fish, shellfish, turtles, and other wildlife.

The water appears red because of the particular depth at which the algae live. Light waves don’t penetrate seawater evenly, and certain wavelengths travel farther than others. The algae that cause red tides grow at depths that absorb green and blue frequencies of light and reflect red ones.

Not all algal blooms are red; some are blue, green, brown, or even purple. Nor do all algae harm humans or animals. Why and how certain species of algae multiply like crazy and wipe out entire swaths of marine life is still a scientific mystery.

The worst red tide on record occurred in 1946, when a mass of algae stretching for 150 miles along the Florida coastline killed more than 50 million fish, along with hundreds of dolphins and sea turtles. Tourists shied away from the beaches as the bodies of dead sea creatures washed ashore. Smaller incidents are more common, but just as costly. In the past decade alone, fishing and tourism industries in the United States have had an estimated $1 billion in losses due to red tides—and the cost is expected to rise.

Editor's note: This story, which originally ran in 2015, was updated in August 2018.

Why Do So Many Diners Look Like Train Cars?

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iStock

No matter how many fine dining options you may have in your area, there’s something about sitting down in a diner that can’t be matched. Their menus are models of American comfort food, from meatloaf to patty melts. The coffee cups are bottomless. There’s usually a toothpick dispensary at the register.

Many diners across the country have one additional identifying trait: They’re shaped like a train car, a sleek and narrow compartment that looks like it belongs on a set of tracks. When and why did this style choice become synonymous with diners?

In a piece for Atlas Obscura, Anne Ewbank shed some light on the practice. The early 20th century saw a rise in entrepreneurs who were interested in meeting the need for casual dining establishments for people hurrying to or from work. Their ambitions had evolved from the lunch wagons of the late 1800s, which provided shelter from weather by putting up awnings or letting people sit inside on stools.

City ordinances, however, made such operations a little tricky: Many food wagons needed to be permanent fixtures in order to avoid the narrow operating hours mandated by communities. Rather than hire a contractor or lease an existing commercial space, people opted to order prefabricated, mobile carts that could be shipped to their location by rail or towed by truck. These dining cars became known as “diners.”

Like the pop-up locations of today, the diners could appear virtually overnight. Most were delivered in one piece; others were modular, requiring minimal assembly, and could offer a greater variety of styles and seating capacities. For small business owners, their affordability and convenience made it possible to strike out on their own. Some manufacturers even offered to repair fixtures by having the diner shipped back to the factory.

The look became so intertwined with fast-dining that some owners recycled old train cars to capture the aesthetic. Today, even diners built from scratch often mimic the narrow, elongated shape so familiar to patrons—a design now borne out of choice rather than necessity. It's a curious bit of history, and one worth pondering the next time you grab a toothpick.

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