This article tests the proposition that, beginning in the 1970s, historic growth of public environmental concern and opposition to waste facilities, as well as changes in the policy environment increasingly encouraged hazardous waste facilities siting to follow the path of least (political) resistance and resulted in environmental inequities. Our longitudinal analysis of sitings in the State of Michigan from 1950 to 1990 reveals a distinct temporal pattern supporting our hypotheses. Whereas significant racial, socioeconomic, and housing disparities at the time of siting were not in evidence for facilities sited prior to 1970, patterns of disparate siting were found for facilities sited after 1970. Thus, we call for environmental justice studies employing longitudinal methods to understand the processes and factors contributing to environmental inequalities with greater consideration to changes in historical context.