Researchers have long observed substantial geographic variation in the use of health care services. This column uses data on health care use among individuals who are uninsured as they approach age 65 and become eligible for Medicare to argue that most geographic variation is the result of supply-side factors that allow providers to exercise discretion over the levels of care provided. Policies aimed at reducing these discrepancies across regions may not only ‘bend the cost curve’, but may also directly reduce health risks arising from individuals receiving ineffective or unneccesary health care services.