Optimal primaries

•We analyze a model of presidential primaries with sequential voting.•The order of the states is determined by a social planner.•It is optimal to order the states from smallest to largest.•It is also optimal to order the states from most informed to least informed.•The results are robust to the possibility of endogenous candidate strategies.

We analyze a model of US presidential primary elections for a given party. There are two candidates, one of whom is a higher quality candidate. Voters reside in m different states and receive noisy private information about the identity of the superior candidate. States vote in some order, and this order is chosen by a social planner. We provide conditions under which the ordering of the states that maximizes the probability that the higher quality candidate is elected is for states to vote in order from smallest to largest populations and most accurate private information to least accurate private information.