The Giant Beavers went extinct at the end of the last Ice Age, roughly 12,000 years ago. Fossils of the Giant Beaver are concentrated around the Midwestern United States in states near the Great Lakes, particularly Illinois and Indiana, but specimens are recorded from Alaska and Canada to Florida. Specimens from Florida have been placed in a subspecies, Castoroides ohioensis dilophidus, based on differences in premolar and molar features.
