Two parallel processes structure American politics in the current moment: partisan polarization and the increasing linkage between racial attitudes and issue preferences of all sorts. We develop a novel theory that roots these two trends in historical changes in party coalitions. Changing racial compositions of the two major parties led to the formation of racialized images about Democrats and Republicans in people’s minds—and these images now structure Americans’ partisan loyalties and policy preferences. We test this theory in three empirical studies. First, using the American National Election Studies we trace the growing racial gap in party coalitions as well as the increasing overlap between racial and partisan affect. Then, in two original survey studies we directly measure race–party schemas and explore their political consequences. We demonstrate that race–party schemas are linked to partisan affect and issue preferences—with clear implications for the recent developments in U.S. politics.