The Dartmouth Atlas of Health Care Website Archive (effective June 30, 2024)

For more than 25 years, The Dartmouth Atlas Project documented striking variations in how medical resources were distributed and used in the United States. The project used Medicare and Medicaid data to provide information and analysis about national, regional, and local markets, as well as hospitals and their affiliated physicians. This approach, which traces its intellectual roots to Jack Wennberg’s original 1973 Science article, established the field of small area variations health services research.

Researchers, policymakers, non-governmental organizations, and the media used the Dartmouth Atlas to better understand inefficiencies and inequities of the U.S. healthcare system. Between 1996-2023, more than 8,700 peer-reviewed articles that referenced the Dartmouth Atlas or used Dartmouth Atlas data and tools were published. And multiple reforms to the health insurance market in the Affordable Care Act (ACA) enacted in 2010 can be traced directly to findings from the Dartmouth Atlas.

With Jack Wennberg’s death and changes to the Center for Medicare and Medicaid Service’s policies related to the provision of claims data for research in 2024, we acknowledge the end of an era in Dartmouth’s history and in the field of health services research more broadly. We thank the research and policy community for their interest and advocacy. Although we will no longer update Dartmouth Atlas tools or calculate new annual rates, this website will continue to provide historical Dartmouth Atlas rates (through 2019) and associated documentation. Stay tuned as a new generation of Dartmouth researchers reflects on the most pressing policy issues of our time and seeks productive ways to contribute to our shared goal of improving health and healthcare for all.


Access data


Explore Medicare data with interactive visualizations


Let us share what we have learned from our data