The geographical service area designated by the Federal Government and assigned to an Organ Procurement Organization (OPO) for recovering organs from all hospitals in that region. DSA designation and OPO assignments are made every four years beginning in 2002 (every two years from 1998-2001) by the Centers for Medicare and Medicaid Services (CMS). Detailed lists of counties within each DSA can be found in Table 9 of the OPO reports at www.ustransplant.org.