Replication data for: The Incredible Shrinking State: Explaining the Territorial Size of Countries

The average size of states within the international system steadily expanded during the 19th century, nearly doubling between 1816 and 1876, and then contracted over the 20th century. In previous work, we found that two key characteristics of globalization, increasing economies of scale and economic openness, as well as regime type, were important explananda for this trend in average state size (Lake and O’Mahony 2003). The rise in territorial size during the 19th century was, in part, the product of a growing number of large, federal democracies made possible by increasing economies of scale in the 19th century, while economic liberalism allowed small, unitary democracies to prosper in the 20th century. In this paper, we analyze how this trend in average state size affects interstate and intrastate conflict. We predict that as average state size increased in the 19th century, larger national territories should become more valuable, leading to more interstate territorial disputes, while demands for smaller states, in the guise of secessionist movements, should decline. Conversely, as average state size declined in the 20th century, we expect interstate conflict to decline while int rastate conflict becomes more prevalent. We test these hypotheses on the pattern of interstate and intrastate conflict since 1816 at both the system and regional levels, and on the issues purported to lead to interstate conflict. We find relatively strong support for our expectations in the pattern of interstate wars and the issues underlying those conflicts. The evidence on intrastate conflict is much more mixed. We speculate that territorial issues may be less central to civil war s, although we present no evidence on this score.