Our chances of living a long and healthy life are influenced by our position in intersecting social hierarchies, but also by our exposure to social policies. My research explores the policy mechanisms by which social inequalities in health are modifiable. In this dissertation, I draw on the Panel Study of Income Dynamics, the longest-running panel study in the U.S., and the National Social Life Health and Aging Project, a nationally representative, longitudinal survey of community-dwelling older adults. I combine these surveys with data on contextual factors to reveal that educational and regional inequalities in health and mortality can transform with shifts in state policy and regional context. The first chapter focuses on the sharp contrast between the South and the rest of the U.S. in health and mortality and examines regional trajectories to sort out when and how region influences health over the life course. The second chapter clarifies the potential for state cigarette taxes to moderate the educational gradient in mortality. In the third chapter, I make the case that advancing the study of health inequalities will require explicit study of the dynamics in fundamental causes through population comparison. I draw on examples from the literature to demonstrate how reframing fundamental causes as systems of exposure can reveal the dynamic nature of health inequality. By studying the extent to which health and mortality inequalities do indeed vary over state and regional contexts, I aim to provide evidence that health inequality is not an intractable problem, but rather something that we produce and maintain through social policy and social structures.