Explaining Cross-State Variation in Independent Identification

The proportion of a state's residents who consider themselves to be independents varies vastly across the states, from a high of 60 percent in Rhode Island to a low of 20 percent in South Dakota. The state-level nature of independence has been ignored by those studying partisanship, who view independence as an isolated individual phenomenon, and by those studying state politics, who examine interparty competition instead. The analysis presented in this article demonstrates that the cross-state variation in independent identification is due to variations in state political characteristics such as interparty competition, organizational strength of parties, type of primary, and primary turnout. However, the effects of these variables are not uniform across all the states. Rather, the effects of interparty competition are specified by region, and primary turnout is only significant in southern states.