Lost votes, divided cities: The unequal electoral geography of invalid voting in Germany’s urban neighbourhoods (2002–2025)

Invalid votes are increasingly salient and politicised given close election outcomes and increasingly fractured party landscapes, yet relatively understudied. While existing studies have emphasised socio-economic, institutional and discontent explanations, they have largely ignored the urban geography of invalid voting. Drawing on IRB (“Inner City Spatial Monitoring Program”) and unique self-collected data in up to 1482 neighbourhoods in 37 German cities in federal elections (2002–2025), we find that invalid votes are quite stable in cities’ neighbourhoods over time and more segregated across neighbourhoods than any other political variable. They occur most in neighbourhoods with higher vote shares for the SPD, CDU, Die Linke, and the AfD and correlate least with the Greens, FDP, votes for other parties, and high turnover. Multi-variate analysis confirms positive associations with peripheral left-behind neighbourhoods with high unemployment and share of foreigners in rich but unequal cities. Rather than social neighbourhood capital (residency duration, family households, population turnover), we find political capital proxied by the presence of party offices in neighbourhoods to account for fewer invalid votes, underlining that local presence of party structures matters. Our exploratory (non-representative) qualitative inquiry with the parties themselves tentatively supports our hypothesised mechanism whereby socio-economically left-behind neighbourhoods are also ‘left-behind’ by organised political parties. This results in lower political capital and greater political disengagement, which drives invalid voting. Theoretically, we argue for taking urban political sociology more seriously in the study of spoilt voting.