How constituent interests influence policy outcomes depends on a country’s political institutions. The examination of Mexican trade policy in two different institutional settings demonstrates that electoral systems influence who receives preferential treatment by politicians. Specifically, when electoral institutions make politicians beholden to territorially specific constituencies, the political clout of an industry stems from its importance within the political jurisdictions that it inhabits. The centrifugal influence of Mexican electoral reforms and the emergence of divided government increased the political salience of subnational economic interests. Where political clout once stemmed from an industry’s importance in the national economy, the political clout of an industry now depends heavily on its importance to subnational economies.