We analyzed mitochondrial DNA variation in the Ringed Salamander, Ambystoma annulatum. Four of six populations studied were fixed for the same haplotype. We attribute this lack of detectable variation to recent colonization of this area, a hypothesis which is supported by paleoecological data and previous biogeographical analysis of the sympatric Spotted Salamander, Ambystoma maculatum. This study demonstrates the potential benefits of comparing biogeographical data across species and suggests that the Hypsithermal Interval may be an overlooked source of important historical impacts for species in the midwestern United States.