This document discusses population health disparities in the United States. It defines disparity and discusses how populations are differentiated by factors like race, ethnicity, income level, and geographic area. It provides examples of population health measures and measures of access to care. Research shows that low-income and minority populations in the US have lower measures of health, access to care, and quality of medical care. The document discusses various social, cultural, environmental, healthcare, and individual reasons for these disparities and outlines upstream, midstream, and downstream interventions to address them.