A Swing-State Theorem, with Evidence

We study the effects of local partisanship in a model of electoral competition. Voters care about policy, but they also care about the identity of the party in power, with most states biassed toward one party or the other (i.e., ‘red’ or ‘blue’). We show that electoral competition leads to maximization of welfare with an extra weight on citizens of the ‘swing state:’ the one that is not biassed toward either party. We show empirically that the US tariff structure is biassed toward swing-state industries, such that a voter living in a non-swing state is treated as being worth 82% as much as a voter in a swing state. This represents a policy bias orders of magnitude greater than the bias found in studies of protection for sale.