By the end of the fourteenth-century AD, Native peoples throughout the midwestern and southeastern regions of North America had withdrawn from major monumental and political centers established in prior centuries. In this article, I present the results of a community-level examination of settlement transformations on the Georgia Coast that I argue are the outcome of this large-scale movement of Mississippian peoples. Specifically, I examine the consequences of the depopulation of the Savannah River Valley, a case of a rapid, historically contingent Mississippian emigration beginning in the fourteenth century AD. My results establish how a large-scale immigration event affected community spatial and political organization and demonstrate that migrants and coastal locals engaged in the collective cultural construction of new identities and lifeways in response to the challenges of negotiating the use of common pool resources, such as fisheries and suitable farmland. Reconstructing the spatial organization of communities can help explain the demographic, economic, and political processes that undergird the cultural materialization of space. Although much remains to be learned about intra-settlement organization at post-Archaic, precolonial sites along the Georgia Coast, this investigation provides new information about the local, community-level spatial response to the fourteenth-century immigration event.