We analyzed the mitochondrial cytochrome b gene of three vagrant Cave Swallow (Petrochelidon fulva) specimens from Illinois, New York, and New Jersey and compared them to published sequences from across the breeding range of the species. All three specimens were assigned to the southwestern United States/Mexico subspecies (P. f. pallida group) on the basis of plumage coloration. Molecular results reveal that all three birds possess unique and novel mitochondrial haplotypes that are closely related to haplotypes from known P. f. pallida individuals. None of the three haplotypes from the vagrant individuals is within the monophyletic clade of haplotypes that corresponds to the Caribbean subspecies (P. f. fulva).