The conservation of species at the periphery of their ranges has been gaining increased attention. The northern map turtle (Graptemys geographica) is a wide-ranging species that is considered globally stable. However, some states/provinces may have only peripheral populations of the species with either few existing populations or a small area occupied. In Mississippi, only a small portion of northeastern Mississippi occurs in the Tennessee River drainage, a drainage occupied by G. geographica, and range maps project that the species may occur in a small fraction of the state in Tishomingo County. However, no specimen or photographic vouchers had previously been collected for the species. We conducted canoe and visual point count surveys within creeks of the Tennessee River drainage to determine if G. geographica is present and, if so, to further assess the distribution and abundance of the species in northeastern Mississippi. We discovered the species in 2 confluent creeks in Tishomingo County, but only 1 appears to hold a viable population. The habitat of these creeks, including bedrock or gravel substrate, is similar to localities previously described for the species; the species was absent from areas surveyed dominated by clay- or sandy-bottomed creeks. Peripheral populations of a species are usually the first populations to exhibit declines, and it is therefore important to manage those populations accordingly and protect their genetic integrity. For these reasons, we suggest listing the species as critically imperiled (S1) and endangered in Mississippi. These designations would afford state protection to what is now likely Mississippi's rarest turtle species.