The dwarf palmetto, Sabal minor, reaches the northwestern limit of its geographic range in McCurtain County, Oklahoma, where it is critically imperiled. We determined that S. minor was more widespread than previously reported; 28 new localities were identified. Populations were associated positively with average annual minimum temperatures (i.e., plants were in the warmest parts of the county), negatively associated with elevation, and the species primarily occurred on silty clay soils. Although S. minor was common in a few areas near Red Slough Wildlife Management Area, it generally was uncommon and typically represented by only a few individuals. Ecological Niche Factor Analysis projected that suitable habitat was concentrated in southeastern McCurtain County, but that potentially suitable habitat was present throughout much of the county.