From Weimar to West Germany: Confessional cleavages, party fragmentation, and far-right voting

How do social cleavages shape party-system fragmentation, and how does this relationship change when parties organize across instead of along these cleavages? We examine the Catho-lic-Protestant divide in Germany from Weimar to the postwar period, exploiting the confes-sional mosaic of Baden and Württemberg. Using data from over 3,000 parishes, we show that fragmentation in Weimar Germany followed a hump-shaped relationship with the local Catho-lic share, peaking in religiously mixed parishes where a cohesive Catholic bloc coexisted with a fragmented Protestant center-right. During the Great Depression, the Nazi Party consolidated the fragmented Protestant vote. After 1945, the cross-confessional CDU weakened the link between religious cleavages and fragmentation. Yet Catholic areas remained less susceptible to far-right voting, a persistence that survey evidence attributes to church influence rather than policy preferences. Overall, our findings show that the effect of social cleavages on political fragmentation hinges on how parties and organizations mobilize them.