How Ethnic Cleavages Divide Voters into Parties: New Methods and Evidence from Sub-Sahara Africa


While ethnicity is recognized as an important political cleavage in Sub-Saharan Africa and beyond, the extent to which ethnicity structures electoral competition is contested. We argue that the interdependence between observed voting patterns and party existence complicate micro-level analyses of voting behavior that parties as exogenously given. In turn, macro-level approaches are prone to bias from ecological inferences where ethnic divides correlate with other cleavages. We shed new light on ethnic voting and party systems by modeling both as the partitioning of voters into parties. Our network-based approach estimates the effect of ethnic cleavages on voters’ partitioning while conditioning on individual and geographic confounders. Based on Afrobarometer surveys, our results show strong and robust effects of ethnic divides between voters on the probability of them choosing different parties and thus the endogenous emergence of ethnically aligned parties. We explore the mechanisms by which ethnicity increases co-ethnic vote choice and alternative, non-ethnic explanations of place, economic interests, and historical contingencies. The methods we propose have the potential to narrow the gap between micro-level studies of electoral behavior and macro-level explanations of party systems.