The Black Belt region of Mississippi and Alabama has long been reported to contain prairies. To assess the extent and distribution of these prairies, this study examined historical accounts of prairie in the region, compiled a map based on surveyors' plat maps from the 1830s and compared the flora of existing prairie fragments with other open ecosystems in the Southeast using data from the literature. Numerous historical accounts attest to the presence in the Black Belt of prairies of varying sizes, discretely bounded by forest. Surveys from the 1830s show that approximately 144,000 hectares of prairie were present in the Black Belt. Fragments of remaining prairie appear most similar in composition with other southeastern prairies, as well as nearby open ecosystems. This evidence suggests that Black Belt prairies were a relatively small but distinctive ecosystem in the region.