In 2020, the United States may face shortages of 45,400 primary care physicians and 46,100 medical specialists-a total of 91,500 too few doctors. Unfortunately, health workforce shortages like these are being advanced as cause for repealing or "defunding" the Affordable Care Act (ACA). The extension of health insurance coverage to millions of Americans is a critical first step toward a healthier America. It would be a national failure to leave millions of Americans without health insurance coverage because they will generate additional demand. Rather, the solution is to find ways to meet that demand. Workforce projections utilizing real data and carefully formulated assumptions to assess how and why supply and demand change over time can greatly assist policy makers in finding those solutions. With implementation of the ACA under way, it is time to understand what lessons such projections can teach, and to begin to heed those lessons.