Chicago, IL — Scientists believe they’ve solved one of the Windy City’s strangest mysteries — the true origin of Chicago’s viral “rat hole.” According to new research, the famed sidewalk imprint that captured worldwide attention may have belonged to a squirrel or muskrat, not a rat after all.
The so-called “rat hole” became a quirky landmark in Roscoe Village after locals discovered what looked like the full-body impression of a rat pressed into a slab of sidewalk cement. Complete with visible limbs, claws, and a tail, the imprint fascinated residents and social media users alike.
From Viral Sensation to Scientific Mystery
The story began when comedian Winslow Dumaine posted a photo of the mysterious impression on X (formerly Twitter) in early 2023. The post quickly went viral, drawing crowds of curious tourists to the quiet neighborhood.
Visitors began leaving coins and small offerings around the site as a makeshift tribute to the “rat,” turning it into an impromptu shrine.
“It wasn’t a bar or an underground club — it was literally a sidewalk,” Dumaine joked in his post that helped propel the phenomenon.
But as foot traffic surged, neighbors started complaining about noise and disruptions. In April 2024, someone attempted to fill in the imprint with plaster. City workers later removed the original slab and placed it in the City Hall–County Building, while a plaque still marks the spot in Roscoe Village.
The Scientific Study That Changed Everything
According to HuffPost, researchers from the University of Tennessee, the New York Institute of Technology College of Osteopathic Medicine, and the University of Calgary analyzed the impression to identify its real origins.
Their findings, published in Biology Letters, suggest that the so-called rat hole wasn’t created by a rat at all.
The team compared photos of the imprint to museum specimens of mammals found in the Chicago area. They eliminated birds, reptiles, and amphibians due to the clear presence of arms, legs, and a tail.
“The creature’s long forelimbs, third digits, and hind paws were too large for a rat but fell into measurement ranges for Eastern gray squirrels, fox squirrels, and muskrats,” the researchers wrote.
They concluded that the most probable culprit was the Eastern gray squirrel, given its abundance in Chicago.
How the Imprint Likely Happened
The study theorized that the imprint was likely the result of a squirrel accident, not a nocturnal rat encounter.
“Cement is typically wet during the day, and rats are nocturnal,” the paper explained. “It’s more likely a squirrel misjudged a leap or slipped from a branch and landed in the wet cement.”
The absence of a distinct tail outline didn’t deter researchers. Hair, they noted, lacks the rigidity to form deep, defined impressions, especially in quick-setting concrete.
From “Rat Hole” to “Sidewalk Squirrel”
In their paper, the scientists humorously proposed a rebranding of the urban legend:
“We therefore propose that the specimen be rechristened the ‘Windy City Sidewalk Squirrel’ — a name more fitting of its likely origins and more aligned with the evidence at hand.”
For years, the “rat hole” served as an unlikely symbol of Chicago’s offbeat charm. Now, it may officially take its place in the city’s folklore — not as a rodent relic, but as a scientific curiosity and accidental squirrel memorial.
What do you think of this surprising discovery? Should Chicago embrace its new “Sidewalk Squirrel”? Share your thoughts in the comments below.
