The shortage of physicians in rural areas is a longstanding and serious problem, and national and state policymakers and educators continue to face the challenge of finding effective ways to increase the supply of rural physicians. To determine the direct and long-term impact of the Physician Shortage Area Program (PSAP) of Jefferson Medical College (JMC) on the rural physician workforce. Retrospective cohort study. A total of 206 PSAP graduates from the classes of 1978 to 1991. The PSAP graduates currently practicing family medicine in rural and underserved areas of Pennsylvania, compared with all allopathic medical school graduates in the state, and with all US and international allopathic graduates. All PSAP graduates were also compared with their non-PSAP peers at JMC regarding their US practice location, medical specialty, and retention for the past 5 to 10 years. The PSAP graduates account for 21% (32/150) of family physicians practicing in rural Pennsylvania who graduated from one of the state's 7 medical schools, even though they represent only 1% (206/14710) of graduates from those schools (relative risk [RR], 19.1). Among all US and international medical school graduates, PSAP graduates represent 12% of all family physicians in rural Pennsylvania. Results were similar for PSAP graduates practicing in underserved areas. Overall, PSAP graduates were much more likely than their non-PSAP classmates at JMC to practice in a rural area of the United States (34% vs 11%; RR, 3.0), to practice in an underserved area (30% vs 9%; RR, 3.2), to practice family medicine (52% vs 13%; RR, 4.0), and to have combined a career in family practice with practice in a rural area (21% vs 2%; RR, 8.5). Of PSAP graduates, 84% were practicing in either a rural or small metropolitan area, or one of the primary care specialties. Program retention has remained high, with the number of PSAP graduates currently practicing rural family medicine equal to 87% of those practicing between 5 and 10 years ago, and the number practicing in underserved areas, 94%. The PSAP, after more than 22 years, has had a disproportionately large impact on the rural physician workforce, and this effect has persisted over time. Based on these program results, policymakers and medical schools can have a substantial impact on the shortage of physicians in rural areas.