The US two-party system was transformed in the 1960s when the Democratic Party abandoned its Jim Crow protectionism to incorporate the policy agenda fostered by the civil rights movement, and the Republican Party redirected its platform toward socioeconomic and racial conservatism. The authors argue that the policy agendas promoted by the two parties through presidents and state legislatures codify a racially patterned access to resources and power detrimental to the health of all. To test the hypothesis that fluctuations in overall and race-specific infant mortality rates (IMRs) shift between the parties in power before and after the political realignment (PR), the authors apply panel data analysis methods to state-level data from the National Center for Health Statistics for the period 1915 through 2017. Net of trend, overall, and race-specific IMRs were not statistically different between presidential parties before the PR. This pattern, however, changed after the PR, with Republican administrations consistently underperforming Democratic ones. Net of trend, non-Southern state legislatures controlled by Republicans underperform Democratic ones in overall and racial IMRs in both periods.