Objective Despite the rise of two‐party politics in the American South, most state legislative elections in the region continue to feature only one major‐party candidate. I offer a new account of changes in partisan contestation of state legislative races in the region that centers on the growing importance of constituency partisanship over time. Method Using an original data set of district‐level presidential vote share between 1984 and 2012, I examine the changing effect of district partisanship on uncontestedness. I then estimate multivariate models predicting uncontested seats in 1988, 2000, and 2012. Results Between 1984 and 2012, the effect of incumbency on uncontestedness declines while the effect of partisanship rises. Conclusion The processes accounting for uncontested seats in southern legislative races have changed. Although uncontestedness in earlier periods was primarily driven by the incumbency advantage, in the contemporary period it is largely a result of the racially driven partisan sort of the southern electorate.