We investigated an old-growth oak-shortleaf pine (Pinus echinata) stand of high ecological integrity in east-central Oklahoma located west of the continuous native distribution of shortleaf pine. With the exception of an abundance of shortleaf pine, the basal area (17.2 m²/ha), density (559.6 trees/ha), and species composition of this unmanaged stand is similar to other old hardwood forests in the Cross Timbers ecoregion. Tree-ring dating indicates that the oldest post oak (Quercus stellata) and shortleaf pine sampled in Shortleaf Canyon were 262 and 230 yr old, respectively. Dendrochronology indicated that drought-related disturbances contributed to several episodic pulses of natural regeneration of shortleaf pine at this site. Coupled with local historical documentation and regional paleoecological evidence, the absence of older pines at this isolated site suggests that P. echinata may have naturally colonized Shortleaf Canyon recently, perhaps during the last 250 yr.