The Evolving Mexican Party System

Abstract

Using a new dataset of roll-call votes from the Mexican Congress, we explore the transformation of that country's legislative party system. Analyzing ideal points, dimensionality, and party cohesion, We show how after the fall of the ruling PRI, the ideological space shifted from cleavages on questions of democratization to more standard left-right divisions. We further demonstrate how this evolution has affected governability and executive-legislative relations. Finally, we link these transformations to similar transformations in the Mexican electorate.