Political parties may obtain different share of the votes in different sub-national electoral districts. The extent of this difference is a measure of party nationalization. The fragmentation of national party systems may grow when different parties compete effectively in different districts. The extent to which national fragmentation resembles district level fragmentation is a measure of the degree of aggregation of party systems. The determinants of party nationalization and party system aggregation are the subjects of an ongoing theoretical elaboration. The present study contributes to this endeavor through a theoretically informed analysis of contemporary electoral trends in Argentina. Most existing theories hold that political parties cross territorial boundaries in order to obtain political benefits that are allocated at the national level. Institutional and social factors determine the value and ease of cross-district coalitions. The Argentine party system allocates highly valuable benefits at the
national level and the Argentine society is culturally homogeneous. Yet, party nationalization and party system aggregation have never been complete and have recently decreased dramatically. Coordination and exchange problems that political parties face account for this unexpected result. Coordination problems derive from high social and institutional variance among electoral districts. A decrease in the value of party labels, associated with party policy
inconsistency, hinders the effective resolution of coordination problems. Exchange problems derive from feeble incentives to promote the cooperation among party members who compete for offices of different level. This study documents these relationships combining the quantitative analysis of electoral, institutional and social data with discussions of historical events. So far, scholarly discussions of party nationalization have paid little attention to coordination and exchange problems. A detailed analysis of national and provincial dynamics in Argentina demonstrates these problems are crucial to account for the territorial extension of parties and party systems.
