Published online by Cambridge University Press: 25 March 2018
The fact that two senators are elected from each state offers the potential for natural paired comparisons. In particular, examining historical and geographic patterns in terms of changes in the number of divided US Senate delegations (i.e., states whose two senators are of different parties) is a useful route to testing competing models of American politics, including theories of split-ticket voting, party polarization, and realignment. Brunell and Grofman (1998) used divided Senate delegations to indirectly examine evidence for realignment. We hypothesized that a partisan realignment will necessarily lead to a cyclical pattern in the number of divided Senate delegations. We predicted that the number of divided Senate delegations at the state level would decline after 1996 because we conjectured that there had been a realignment cusp around 1980. We tested this prediction with data from 1952–2016 and our prediction was confirmed.