Salt Wars

Salt was a key fiscal resource in premodern Europe. The ability of states to appropriate salt shaped patterns of fragmentation and consolidation of territories. We propose a model demonstrating that when and where salt was non-appropriable by a central authority, it produced more fragmented partitions. Territories with non-appropriable resources could fund rebellion and resist incorporation, which made conquest of such territories unprofitable. In equilibrium, such territories were more likely to remain independent. To test this hypothesis, we construct a new dataset of 251 historical salt sites, classify them by extraction technology, and exploit temperature variation driven by the Little Ice Age as a source of exogenous identification. Colder temperatures reduced coastal/marine salt production, raising the relative value of inland salt. Where inland salt was appropriable by a central authority, specifically rock salt, we find this temperature shock generated more consolidation. Where it was dispersed and non-appropriable, specifically salt from brine springs, it produced greater fragmentation.