Contagion or Confusion? Why Conflicts Cluster in Space


  • Author’s note: We thank Sabine Carey, Indra de Soysa, Hanne Fjelde, Nils Petter Gleditsch, Phillip Schrodt, the editor of ISQ, and four anonymous reviewers for valuable comments. All reported analyses were conducted in Stata 9.2 and R 2.5.0. Replication data and command files are available via the Dataverse Network Project ( and the ISA data archive page (


Civil wars cluster in space as well as time. In this study, we develop and evaluate empirically alternative explanations for this observed clustering. We consider whether the spatial pattern of intrastate conflict simply stems from a similar distribution of relevant country attributes or whether conflicts indeed constitute a threat to other proximate states. Our results strongly suggest that there is a genuine neighborhood effect of armed conflict, over and beyond what individual country characteristics can account for. We then examine whether the risk of contagion depends on the degree of exposure to proximate conflicts. Contrary to common expectations, this appears not to be the case. Rather, we find that conflict is more likely when there are ethnic ties to groups in a neighboring conflict and that contagion is primarily a feature of separatist conflicts. This suggests that transnational ethnic linkages constitute a central mechanism of conflict contagion.