Hospital referral regions (HRRs) represent regional health care markets for tertiary medical care. Each HRR contains at least one hospital that performs major cardiovascular procedures and neurosurgery. HRRs were defined by assigning HSAs to the region where the greatest proportion of major cardiovascular procedures were performed, with minor modifications to achieve geographic contiguity, a minimum population size of 120,000, and a high localization index. The process resulted in 306 hospital referral regions. More information on how HSAs and HRRs were defined is available in our Appendix on the Geography of Health Care in the United States.

From the Dartmouth Atlas of Health Care

These Hospital Referral Region (HRR) boundaries were obtained from the Dartmouth Atlas of Health Care website on Mar 18, 2020.

For a detailed description of how these areas were defined, go to page 294 in the Appendix of the Geography of Health Care in the United States.