<p>Elections are not only about how many votes candidates win, but also about where those votes come from. Yet we know less about how the geography of electoral support changes when candidates coordinate across offices through electoral alliances. I study Brazil’s 2020 municipal elections, where mayoral and city-council races are held on the same day under distinct electoral rules, and argue that these alliances can reorganize executive support through a coalition-coordination mechanism: allied council candidates with geographically concentrated personal-vote bases increase mayoral vote concentration within their local strongholds, making legislative dominance areas partially overlap with the supported mayoral candidate’s dominance areas. Using polling place election returns, I construct fine-grained measures of within-municipality vote concentration and estimate polling place fixed-effects models linking mayoral concentration to the concentration of allied council candidates. To address endogeneity, I instrument allied concentration with a Friends-and-Neighbors measure based on where allied council candidates are registered to vote. The results show that increases in allied council candidates’ local overrepresentation translate into greater local overrepresentation for the supported mayoral candidate. The findings are robust to alternative spatial measures, controls for localized mayoral campaign spending, and placebo coalition assignments. Overall, the analysis shows that coalitions can shape not only aggregate electoral performance but also the territorial structure of representation by aligning executive and legislative strongholds.</p>