In 2006, the Association of American Medical Colleges recommended a 30% increase over 2002 enrollment in U.S. medical schools by the year 2016, particularly in areas with rapid population growth during the past 25 years or where the population was projected to grow rapidly in future years. Both MD-granting and DO-granting schools subsequently expanded enrollment. To examine the relationship between ongoing medical school expansion and state-level measures of population need and workforce capacity, the authors used established national health workforce and training site datasets to compare total medical school enrollment (2000-2010) with change in population, medical student retention in state (those returning to practice in the state where they graduated), and primary care supply.From 2000 to 2010, U.S. population increased 10% (median state population growth 7.4%). Median state total MD and DO medical school enrollment growth was 14.7%, with nine states increasing enrollment by more than 50%. Medical student retention rates varied from 9.8% to 67%. A wide variation in concordance and discordance between medical school enrollment to population growth and to medical student retention rates existed across states. States also demonstrated concordance or discordance between medical school enrollment and supply of primary care physicians.The authors recommend strategies for expansion that may help meet the population's need for primary care physicians and improved geographic distribution of specialties. Expansion of graduate medical education must also be aligned with population need, necessitating coordination of workforce planning.