“Driven by population growth and aging, the total number of office visits to primary care physicians is projected to increase from 462 million in 2008 to 565 million in 2025. After incorporating insurance expansion, the United States will require nearly 52,000 additional primary care physicians by 2025.”

Src:
Petterson, Stephen M., Winston R. Liaw, Robert L. Phillips, David L. Rabin, David S. Meyers, and Andrew W. Bazemore. 2012. “Projecting US Primary Care Physician Workforce Needs: 2010-2025.” The Annals of Family Medicine 10 (6): 503–9.

The study was based on data from the annual Medical Expenditure Panel Survey (MEPS), conducted by the U.S. Department of Health & Human Services.

In addition to the MEPS data, the CDC also produces annual estimates of physician office visits, as well as hospital visits via it’s National Ambulatory Medical Care Survey (NAMCS) as well as its National Hospital Ambulatory Medical Care Survey (NHAMCS). Tables of recent survey results are available here. We’ve not yet found a forecast for hospital visits, but we’ve aggregated NAMCS and NHAMCS figures going back to 2000 here.