Baltimore's rat problem is bad enough that at one point, rats tunneled so intensely beneath a particular area of pavement that when garbage collectors drove over it, their truck sunk up to its axles. Rats in the vicinity took full advantage of the mishap and swarmed the truck, gorging on the garbage inside.

Baltimore also enjoys the dubious distinction of being a hotspot for rat-related research, beginning during World War II and continuing today, much of it carried out at Johns Hopkins University.