'Chicago Rat Hole' is not imprint of rat, study suggests

CHICAGO (WGN) — A new study suggests that Chicago's iconic sidewalk rat hole is likely not the imprint of a rat at all.

In an article published by The Royal Society, a research team compared and analyzed the measurements of the "Chicago Rat Hole" to eight rodent species commonly observed in the Chicago area.

According to the study, the imprint is likely of a squirrel.

"Discriminant function analysis indicated a 98.67% likelihood that the ‘Chicago Rat Hole’ was a squirrel, with classifications split between the eastern grey squirrel (50.67%) and the fox squirrel (48.00%). Given local population densities, an eastern grey squirrel likely represents the most parsimonious species-level match," the article states.

The study continues, adding that the elongated forelimbs and digits on the sidewalk impression exceeded the measurements of a brown rat. 

"Given the relative abundance of Eastern grey squirrels in the Chicago area compared to the much rarer fox squirrel or muskrat, incorporating density-based likelihoods into our interpretation would likely favour Eastern grey squirrels as the most probable identity," the article says.

The article ends by humorously proposing that the city rename the imprint to the "Windy City Sidewalk Squirrel."

Before being removed by the city, the “Chicago Rat Hole” was located in the 1900 block of West Roscoe Street in the city’s Roscoe Village neighborhood.

It gained national attention after a picture of it was posted to “X” — and went viral. A Chicago couple even got married at the tourist attraction.