This paper examines whether control of patronage jobs significantly increased a political party's probability of winning elections in U.S. states. We employ a differences-in-differencs design, exploiting the fact that there is considerable variation in the dates different states adopted civil service reforms. We find evidence consistent with the hypothesis that political parties in U.S. states were able to use patronage to increase the probability of maintaining control of their state legislatures and statewide executive offices. We also find evidence that an "entrenched" party in power for a longer time period can use patronage more effectively than a non-entrenched party. We consider several alternative hypotheses that might plausibly account for the patterns in the data, but find no evidence to support them.