Twenty-year trends in regional variations in the U.S. physician workforce.

Large differences in the regional supply of physicians have challenged traditional methods of determining the "right" workforce rate. With continued growth expected in the number of U.S. physicians per capita, this study examines changes in regional variation over time to provide perspective on where future physicians are likely to locate. There was a slight reduction in workforce variation during the past twenty years as the aggregate supply per capita grew more than 50 percent. Most physicians located in regions with an already large supply. Given these persistent patterns, the population benefits of further growth in the physician workforce are uncertain.