The Affordable Care Act’s expansion of insurance coverage is expected to increase demand for primary care services. We estimate that the national increase in demand for such services will require 7,200 additional primary care providers, or 2.5 percent of the current supply. On average, that increased demand is unlikely to prove disruptive. But when we examined how this increased demand will be experienced in different areas of the country, we found considerable variability: Seven million people live in areas where the expected increase in demand for providers is greater than 10 percent of baseline supply, and forty-four million people live in areas with an expected increase in demand above 5 percent of baseline supply. These findings highlight the need to promote policies that encourage more primary care providers and community health centers to practice in areas with the greatest expected need for services.