Chicago’s famous rat hole was never a rat, but a squirrel in disguise

Nature · Published 3 October 2026 Swipe more like this →

In short: A viral sidewalk imprint in Chicago, long celebrated as a gritty symbol of the city’s rodent problem, has been debunked by science. Researchers using comparative anatomy and digital modeling have confirmed the creature that left its mark in wet concrete was actually a squirrel, not a rat at all.

The Chicago rat hole, located in a sidewalk slab in the Roscoe Village neighborhood, became a local sensation in January 2024 after a photograph by artist Winslow Dumaine went viral on X. The impression, which clearly captured the shape of an animal’s body, tail, and three limbs, quickly evolved into a cultural icon. Locals treated the site as a shrine, leaving offerings like coins and candles, and it even hosted weddings and a music festival. The imprint was widely viewed as a testament to the city’s resilient, if somewhat rat-plagued, spirit.

In 2025, a study published in Biology Letters sought to identify the animal behind the mystery. Researchers examined eight potential suspects, including the brown rat, house mouse, and two squirrel species: the eastern gray squirrel (Sciurus carolinensis) and the fox squirrel (Sciurus niger). By analyzing public photographs that included coins of known dimensions, the team created 75 virtual models to estimate the animal's physical proportions. They compared these measurements against museum specimens to determine the culprit's identity.

The analysis concluded that the impression was not a rat, but a squirrel. While the results could not definitively distinguish between the eastern gray squirrel and the fox squirrel, the study highlighted how scientific techniques typically reserved for fossil investigations can be applied to modern community folklore. Although the original concrete slab was removed from the sidewalk in April 2024 and relocated to City Hall, the site remains memorialized with a plaque, serving as a curious intersection of urban legend and rigorous anatomical science.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Why the common city rat remains our most persistent and misunderstood urban neighbor.
• These burrowing rodents built a massive underground city the size of a small country.
• Are Warsaw's urban squirrels actually more stressed by human presence?
• The black rat is a global survivor that reshaped ecosystems and human history
• The fox squirrel is North America's largest tree squirrel, thriving from attics to forests.
• Are blind snakes truly primitive, or did they evolve their subterranean lifestyle later?
• Before birds ruled the skies, some dinosaurs experimented with bat-like membranous wings.
• Why the world's most common owl genus spent a century in taxonomic confusion
• The sawshark uses its serrated snout as both a sensory array and a weapon.
• The Scorpaenidae family hides a masterclass in evolutionary defense and invasive ecological dominance.
• Are turtles actually reptiles? The shifting definition of the clade known as Sauria
• Why these bulky South American birds are the ultimate feathered security guards

More in Vertebrates · More in Nature · Latest · A–Z · All topics