The sourcing of exotic raw materials provides a window into the social networks of ancient peoples. Here we source copper from four archaeological contexts at the Mound City Group, a UNESCO World Heritage site and major Hopewell ceremonial site in south-central Ohio, USA. Results of laser ablation–inductively coupled plasma–mass spectrometry indicate the use of copper at Mound City from both the Great Lakes Copper District and the southern Appalachians. Forty-two percent of the Mound City sample was classified as southern Appalachian copper, a higher percentage than for any other large Ohio Hopewell site tested. The use of Appalachian copper has not been documented in earlier, pre-Hopewell contexts in the central Ohio Valley. This new pattern correlates with both an increased demand for copper and the development of broader-based social networks connecting the central Ohio River Valley with the Southeast. This context is different from and complementary to that of the “copper trail” to the north established hundreds of years earlier.
