When have violent civil conflicts spread? Introducing a dataset of substate conflict contagion

The spread, diffusion, spillover, or contagion of violent civil conflict – including insurgencies, coups, or other internal armed conflict – across international borders is of great concern to civil war scholars and international security policymakers alike. For instance, great power military interventions are often predicated in part on the belief that if a given conflict is not stopped now, it may spread and destabilize an entire region. Nevertheless, our understanding of this phenomenon of ‘substate conflict contagion’ is hindered by the lack of a comprehensive and accurate universe of cases. In this article I introduce an original dataset of cases and non-cases of substate conflict contagion between 1946 and 2007. The key difference between my dataset and other datasets of this phenomenon is that I require in my definition of contagion not only the spatial and temporal proximity of two conflicts, but also a documented causal link between them. After introducing the dataset and the process by which it was constructed, I show that substate conflict contagion by my definition is significantly less common than previous scholarship and policymaker rhetoric suggest, and that its correlates – and potentially the best methods with which to measure those correlates – are different from prior research as well. Policy implications are considered, and applications of this dataset for future conflict research are explored.