Do South-South Trade Agreements Increase Trade? Commodity-Level Evidence from COMESA

South-South trade agreements are proliferating: Developing countries signed 70 new agreements between 1990 and 2003. Yet the impact of these agreements is largely unknown. In this paper, we focus on the static effects of South-South preferential trade agreements stemming from changes in trade patterns. Specifically, we estimate the impact of the Common Market for Eastern and Southern Africa (COMESA) on Uganda's imports between 1994 and 2003. We use detailed import and tariff data at the 6-digit Harmonized System level for more than 1,000 commodities. Based on a difference-in-difference estimation strategy, we find that—in contrast to evidence from aggregate statistics—COMESA’s preferential tariff liberalization has not considerably increased Uganda’s trade with member countries, on average across sectors. The effect, however, is heterogeneous across sectors. Finally, we find no evidence of trade-diversion effects.