During an investigation of caves in Taylorsville Metropark, near Dayton, Ohio, vertebral remains of rattlesnake (Crotalus sp.) and garter snake (Thamnophis sp.) were recovered from sites radiocarbon dated to a the historical period (~146 years before present) and to the Hopewell Archeological period (~1,433 years before present). The latter specimens recovered represent the some of the oldest sub-fossil evidence of the migration of these genera into the plains and forests of Ohio. A review of scientific and historical records for each genus indicates thatThamnophis appeared in the region prior to the end of the Pleistocene Epoch and persisted in abundance up to the present day. Crotalus, however, likely appeared sometime after the end-Pleistocene before the Holocene Epoch’s Medieval Warm Period. Historical reports of this genus further suggest that the decline of Crotalus in Ohio likely began sometime before 1882 CE: a trend that persists to this day, as rattlesnakes are absent throughout western Ohio.