The literature on the origin and development of the German Social Democratic Party (SPD) is vast. The puzzle about the steady increase in electoral strength of a party whose voters were subjected to systematic harassment and intimidation throughout the political history of the Empire has fueled the imaginations of every generation of historians and political scientists. What explains the rise in electoral strength of the SPD, and how did it become the largest political party in the Reich? I draw on a wealth of new economic data unavailable to previous scholars in order to reexamine this classic research question in comparative politics.

An analysis of the cross-sectional and temporal variation in the electoral strength of the SPD allows me to test a range of additional observable implications of the theoretical framework developed in this book. The first part of the book (Chapters 1–4) developed a number of hypotheses about the relationship between economic and political conditions in German districts and the “costs of electoral repression” encountered by private actors. I showed that the costs were higher in districts characterized by high levels of economic heterogeneity. The costs of electoral intimidation for state employees – such as policemen and tax collectors – also varied significantly across districts and were higher in districts characterized by high levels of political fragmentation among right- wing parties, where the outcome of a race was determined in runoffs. This chapter explores an additional observable implication of this analysis: I examine the factors that affected the variation in the willingness of voters to take political and economic risks by supporting opposition candidates. The corollary of the empirical findings presented in the first part of this book is that political support for Social Democratic candidates should be higher in districts where state employees and private actors faced higher relative costs of electoral intimidation.