This article provides a new conceptual and empirical analysis of party system nationalization, based on four different measurements. Unlike previous nationalization studies, these measurements conceptualize party system nationalization on the basis of electoral performance in national (general or federal) and sub-national (state) elections. After introducing these measurements we apply them to 16 general and 351 state elections in India, the world’s largest democracy with strong sub-national governments. By incorporating state election results we are able to demonstrate that: (1) the pattern of denationalization in India has been more gradual than assumed in previous studies of party system nationalization; (2) denationalization in recent decades results less from dual voting (vote shifting between state and federal elections) than from the growing divergence among state party systems (in state and federal elections); (3) the 2014 general election result, although potentially transformative in the long run, provides more evidence of continuity than change in the short run.

This article has the purpose to assess if and how party system nationalization affects individual voting behaviour. Previous studies on party system nationalization have focused on systemic processes, exclusively dealing with aggregate data. The authors address this topic from a new empirical perspective, arguing that party system nationalization could act as a context dimension interacting with the vote choice function. How does this specific context dimension moderate the explanatory power of individual-level characteristics? On which determinants of vote choice does party system nationalization have a greater impact? To answer these questions, the authors focus on 23 European countries through the use of the 2009 European Election Study. The empirical analysis shows that in nationalized contexts the impact of the left-right dimension on party support is higher than in territorialized contexts, whereas that of class as well as of culture-related variables is lower. The authors also discuss the implications of these findings.