On March 14, 2026, as the city of Chicago prepared to celebrate St. Patrick’s Day, a familiar spectacle unfolded along the banks of the Chicago River. For the 64th consecutive year, the waterway was transformed into a glowing emerald ribbon, captivating thousands of locals and visitors who flocked downtown to witness the dramatic annual ritual. The river’s sudden shift to a brilliant green hue, lasting for roughly five hours, was the work of a dedicated crew: 130 members of the Journeymen Plumbers Local Union, who have shepherded this tradition since its inception in 1962.
The dyeing process began promptly at 10:00 a.m. near Michigan Avenue and Wacker Drive, with participants donning their union colors and readying hoses mounted on both architecture tour boats and smaller motorboats. As the boats cruised the river, nearly 40 pounds of a mysterious powdered dye—believed to be vegetable-based and confirmed to be non-toxic—were released into the water. The formula, closely guarded by union members and city officials, remains a secret, adding an extra layer of intrigue to the event. According to reporting by WMAQ and the Chicago Tribune, the dyeing spectacle stretched from the Columbus Drive bridge all the way to Orleans Street, stopping just before Wolf Point. Within minutes, the river was awash in a vibrant shade of green, its color at its most dazzling during the first hour.
For many Chicagoans, the dyeing of the river is more than just a quirky city tradition—it’s a symbol of the city’s deep-rooted Irish heritage and a celebration of the communities that have shaped its identity. As LADbible explains, the origins of this annual ritual trace back to a happy accident in the early 1960s. At the time, the local plumbers’ union, led by business manager Stephen Bailey, was using an orange dye to trace leaks in city buildings. When the dye hit the water, it turned a vivid emerald green. Bailey, a friend of then-mayor Richard J. Daley, saw the potential for something special. Daley initially suggested dyeing Lake Michigan itself—a grand idea, but ultimately too ambitious. Instead, they settled on the Chicago River, launching what would become an enduring St. Patrick’s Day hallmark.
The event’s timing is no accident either. The river dyeing typically takes place on the Saturday before St. Patrick’s Day, coinciding with the city’s downtown parade. This year, the parade followed the dyeing, marching under the theme “Faith, Peace and Unity,” and honoring Chicago’s own Pope Leo XIV. The celebration drew crowds to the city center, with thousands lining bridges and sidewalks, snapping photos and soaking in the festive atmosphere. As Choose Chicago—the city’s tourism bureau—enthusiastically notes, “The annual Chicago River dyeing is one of the most unique St. Patrick’s Day celebrations in the world… a beloved tradition that dates back over half a century. The brilliant green color only lasts a few hours, so be sure to catch a glimpse and snap some photos before heading off to a local tavern to enjoy some green beer.”
This year’s event, however, featured a surprising twist. As reported by Cox Media Group, sharp-eyed spectators spotted what appeared to be shark fins slicing through the green waters. But there was no need for alarm—these were no aquatic predators, but rather a clever promotional stunt for Netflix’s upcoming film “THRASH.” The movie, set for release next month, is a disaster flick in the vein of “Sharknado,” featuring a Category 5 hurricane that sweeps sharks into a coastal town. The stunt, which saw fake fins gliding through the dyed river, added an unexpected layer of spectacle to the day’s festivities and sparked a flurry of social media posts.
Chicago’s embrace of all things Irish runs deep, and the river dyeing is just one expression of the city’s rich heritage. The roots of this connection stretch back to the 19th century, when waves of Irish immigrants arrived in Chicago during the Great Famine, taking on labor-intensive jobs such as building canals and railroads. Over time, Irish Americans gained significant influence in local politics—most famously through figures like Mayor Daley—and built strong Catholic communities in neighborhoods like Beverly, Mount Greenwood, and Bridgeport. Today, their legacy is woven into the fabric of the city, celebrated not only in parades and river dyeing, but also in the enduring spirit of Chicago’s neighborhoods.
Despite the spectacle’s popularity, the dye’s exact composition remains shrouded in mystery. Officials and union members are tight-lipped, revealing only that the formula is non-toxic and, according to widespread belief, vegetable-based. This secrecy has only fueled public fascination, with speculation swirling each year about what exactly gives the river its otherworldly glow. The city is quick to reassure environmentalists and concerned citizens alike: the dye does not harm the river’s ecosystem, and the water returns to its usual state within a matter of hours.
For those hoping to catch the green river in person, timing is everything. The color is most vivid during the first hour after the dye is released, and it fades gradually over the next several hours. By the time St. Patrick’s Day itself rolls around—March 17th—the river has already returned to its normal hue. As LADbible points out, “if you are in the Chicago area and were hoping to see the green Chicago River on St Patrick’s Day, you may well have left it too late as the dye only stays around for a matter of hours.” This fleeting quality is part of what makes the tradition so special, drawing crowds who don’t want to miss their annual chance to witness the transformation.
The dyeing of the Chicago River has become so iconic that it’s featured in TV shows, movies, and countless social media feeds. It’s a bucket-list event for many, and a point of pride for the city—a vivid reminder of Chicago’s ability to celebrate its heritage with both reverence and a healthy dose of fun. As the parade bands march, the crowds cheer, and the river glows green (if only for a few hours), Chicago’s St. Patrick’s Day stands out as a celebration unlike any other.
After more than six decades, the tradition remains as vibrant and beloved as ever, a testament to the city’s enduring spirit and its unique way of honoring its past while embracing the present.