Red River Jasper, a lithic material found in the Red River drainage, is an understudied chert that was widely used by prehistoric populations in this region from the Archaic to late prehistoric (Caddo) periods. Despite its common occurrence at sites along the Red River, this tabular chert has received little attention compared to other raw materials on the eastern margin of the Southern Plains. Although the material is macroscopically diverse, ranging in color from brown to yellow to red, microscopic analysis indicates that the material is relatively homogeneous and likely came from a limited set of sources. The archaeological distribution of Red River Jasper, geological evidence, and a stream survey of gravels demonstrate that the primary bedrock source was located in the Johns Valley Formation of the Ouachita Mountains and was carried downstream by the Kiamichi River into the Red River