Chicago

Chicago's Infamous "Rat Hole" Likely the Work of a Squirrel, New Study Reveals

AI Assisted Icon
Published on October 15, 2025
Chicago's Infamous "Rat Hole" Likely the Work of a Squirrel, New Study RevealsSource: Google Street View

The long-standing mystery surrounding the notorious "Chicago Rat Hole" that captured the curiosity of many has been the subject of a recent scientific debate, with new research suggesting it was never a rat's doing after all. According to WGN-TV, a study published by The Royal Society claims the impression commonly attributed to the gnawing of a rat likely belongs to a squirrel, potentially altering the silhouette's storied place in the city's cultural lore.

In a detailed analysis comparing the sidewalk impression to eight sympatric rodent species, the study put forth a "98.67% likelihood that the 'Chicago Rat Hole' was a squirrel," specifying the eastern grey squirrel and the fox squirrel as probable culprits. The elongated forelimbs and digits observed far exceed what one might expect from a brown rat, casting significant doubt on long-held assumptions about the urban mark. The article humorously goes on to suggest that perhaps the city should consider renaming the imprint as the "Windy City Sidewalk Squirrel," in acknowledgment of its true artisan.

Fad or not, the imprint drew widespread attention to the extent that tourists took pictures, and one particular Chicago couple decided to celebrate their union right at the location before it was removed. The impression once sat on the 1900 block of West Roscoe Street, a fact not lost on the local community that embraced the Rat Hole as a quirky and unexpected piece of their neighborhood tapestry.

Simultaneously, ABC7 Chicago reported findings published in Biology Letters, affirming similar conclusions about the rat hole's identity. Scientists have narrowed down their analysis, noting that the outline is not only rodent-esque but concretely squirrel in nature, challenging perceptions of rodents among the denizens of Chicago, where the line between urban wildlife and folklore often blurs.

The now-famous impression used to lie near Roscoe Street and Damen Avenue, becoming something of an urban icon before its removal. As the narratives of rats and squirrels entwine and clash on the streets of Chicago, the scientific community has brought to light a different, perhaps less fearsome, architect behind the infamous sidewalk anomaly that is the "Chicago Rat Hole," or as it might soon be known, the mark not of a rat, but of a squirrel, in the heart of the Windy City.