A somewhat less dire projection comes from the Council on Graduate Medical Education, which anticipates a shortfall of some 85,000 physicians by 2020. Yet others question whether there is a physician deficiency at all, or whether somehow coming up with tens of thousands of new physicians would even be desirable. Dartmouth’s Goodman contends that anecdotal reports of shortages merely reflect a combination of inefficient health care systems and recruiting problems in some geographic areas and specialties. There’s evidence to support that view: A 2006 survey by the U.S. Government Accountability Office indicates that, from 2000 through 2004, no more than 7% of Medicare patients nationwide reported problems finding a doctor.

“It’s what physicians do that’s important, not how many there are,” says Goodman. Some health care systems are much more efficient than others and require many fewer physicians to serve a population of a particular size. Moreover, having a larger supply of doctors isn’t necessarily beneficial, says Goodman, whose research suggests that regions and states with very high supplies of specialists have a lower quality of care and no difference in survival rates.

Finding a way to get the right number of physicians, in an appropriate mix across specialties and geographic regions, is an extraordinarily tall order. To the extent that there may be a coming shortage of doctors, the most straightforward solution would be to mint more. The Association of American Medical Colleges has called for a 30% increase in U.S. medical school enrollment by 2015, a change that could add 5,000 physicians annually, and new medical schools are being planned in about two dozen states, according to Cooper. “Still, creating a school is a huge financial undertaking, and some of these schools may never materialize,” Cooper says.

Then there’s the question of where new doctors would train. Many policy experts want the federal government to lift the 1997 cap on the number of residencies it pays for through Medicare. A U.S. Senate bill, introduced in February, would expand residency programs in 24 states facing critical physician shortages, increasing national training slots by 1,222. There’s also a House of Representatives version, but neither bill seems likely to advance quickly.

Further complicating matters is the role of foreign medical school graduates, who today fill one in four residency slots. Some experts argue that the United States should stop importing such a big percentage of its doctors. “Our continual reliance on the rest of the world for a major portion of our physicians creates a drain on the global workforce, especially for the poorest countries,” says Fitzhugh Mullen, a professor of pediatrics and health policy at George Washington University. If medical school enrollments increase, even without lifting the federal spending cap on residencies, Mullen wants U.S. graduates to fill most of the existing training slots. But others, including the MGH’s Blumenthal, question whether it would be possible to increase the overall number of physicians practicing in the United States while also reducing the number of foreign medical school graduates.

Boosting physician supply is also complicated by the impending departure of a large segment of the current pool. A third of physicians practicing in the United States are older than 55 and likely to retire during the next 20 years. Their exodus could have a profound impact on the availability of medical services, particularly because the new generation of doctors tends to look at its role differently. “Generation Xers are more in tune with their families and personal lives than I was, and they value their time off,” says David Nichols, 59, who notes that his younger colleagues at Whitestone Family Practice, near Virginia’s Chesapeake Bay, log much shorter workweeks than he did at their age. “I don’t fault them for it, but you just don’t get the same work ethic these days.”

What’s more, many new doctors are women, who made up just 10% of practicing physicians in 1980 but comprise half of today’s medical students. That is also affecting the workforce, because young female physicians, even more than their male colleagues, seem determined to balance careers with family life. Jane Gudakunst, a family practitioner, ultimately gave up clinical practice in favor of a part-time position in hospital education in Clarion, Pa. Gudakunst knows firsthand the hours older physicians worked, having watched her father toiling for years in his own small-town practice. “It would take two or three physicians today to keep pace with what my father did,” she says. “That’s not what I want for my life.”