The Nationalization of Parties and Party Systems

Political parties and party systems exhibit widely varying degrees of nationalization, that is the extent to which a party receives similar levels of electoral support throughout the country. The level of party nationalization has a prominent effect on such important factors as the survival of democracy, the types of issues that dominate political competition, legislative behaviour and public policy. In spite of its importance, party nationalization has been neglected in the comparative politics literature. Our article makes two contributions. First, it provides a measure of party and party system nationalization, based on the Gini coefficient, that is superior for comparative analysis to those employed to date. Second, it utilizes these measures to analyse nationalization in 17 democracies in the Americas, the first time nationalization has been examined empirically outside the advanced industrial democracies. The measure underscores the widely varying degrees in nationalization across party systems, within party systems over time, across parties within countries and within parties over time.