In this national study of 438,895 physicians, 45% provided care to hospitalized patients and 7% provided critical care. At the high estimate of patients requiring hospitalization at the projected peak of the pandemic, 18 states and Washington, DC would have patient to physician ratios greater than 15:1 (a level associated with poor outcomes among hospitalized patients). There was considerable geographic variation in the availability of physicians: 41% of hospital service areas did not have a physician with critical care experience.