This article introduces the concept of patronage regimes and, through it, extends the research on American party development. No systematic empirical inquiry into the operation of American patronage practices has yet been undertaken. Its analysis investigates the strategic allocation of public jobs by party elites to enhance cadre performance in presidential elections. Utilizing a dataset of 49,000 Senate-confirmed, presidential appointments, presidential patronage removals between the years 1829 and 1917 are analysed. Two distinctive patronage regimes are identified: an antebellum regime structured by pure-and-simple spoils politics and a postbellum regime conforming to principles of machine rationality. Factors central to the process of regime transformation are pinpointed. The presence of two successive patronage regimes highlights the importance of endogenous political incentives and elite strategic choice to the emergent character of party organization, shedding new light on the historical development of these pre-eminent nineteenth-century American political institutions.