The geophysics of community, place, and identity in the Mississippian Illinois River Valley

•Geophysical data allow us to trace how social relationships and identities changed over time.•Religion played a key role in constructing Mississippian spaces and shared identities early on.•Warfare necessitated the reconfiguration of town plans, religious practices, and relationships.•As regional networks declined, a new unified Mississippian tradition emerged in the Illinois Valley.