Obsidian is an exotic lithic resource rarely found in Oklahoma, yet it still occurs in the archaeological record. This project utilized Energy Dispersive X-ray Fluorescence (EDXRF) Mass Spectrometry to geochemically source 110 obsidian artifacts from Oklahoma in various private collections and museum collections. These 110 EDXRF samples were added to the existing 220 obsidian artifacts from Oklahoma previously studied to synthesize the data. My research question is: what spatial patterning is expressed by obsidian in Oklahoma, and what do these patterns reveal about cultural interaction through time? I utilized the interpretive framework of conveyance zones and cultural interaction patterns to interpret the results. All spatial and temporal data was process with ArcGIS to parse out the spatial and temporal distribution of obsidian in Oklahoma. The 110 EDXRF samples resulted in eight chert artifacts, which were removed from the study, leaving 102 EDXRF samples combined with the previous 220 samples totaling 322 obsidian samples in Oklahoma subjected to source characterization. The remaining 102 EDXRF samples from this study resulted in the majority of the obsidian artifacts sourcing to either the Cerro Toledo Rhyolite or Valles Rhyolite obsidian sources in the Jemez Mountains in New Mexico. Obsidian from Malad, Idaho and to a lesser extent Obsidian Cliff, Wyoming were also well represented in the 102 EDXRF samples. Outliers include obsidian from Buck Mountain, California, Timber Buttes, Idaho, and at least one unknown obsidian source. The results of the synthesized data of the combined 322 obsidian samples from Oklahoma illuminated shifting cultural interaction patterns between the Southern Plains (Oklahoma) and adjacent regions. Until the Late Precontact Period (1,250 – 450 B.P.) and excluding the Paleoindigenous Period (prior to 7,950 B.P.), people on the Southern Plains preferred obsidian from Malad and Obsidian Cliff overall, suggesting a cultural interaction pattern stretching northward through the Central Plains toward Idaho and Wyoming. During the Late Precontact Period those preferences and cultural interaction patterns shifted toward obsidian from the Jemez Mountains in New Mexico with Cerro Toledo Rhyolite being favored by people in the Oklahoma Panhandle, and Valles Rhyolite in western Oklahoma. During the Postcontact Period (450 – 200 B.P.) people in the past in Oklahoma preferred obsidian the Valles Rhyolite obsidian from New Mexico.