There is no question that access to primary care is critical for population health. Currently, more than one in 10 U.S. residents resides in a county with fewer than one primary care physician per 2,000 people, and the demand for primary care will increase as the population grows and ages, chronic conditions increase, and insurance coverage expands (UnitedHealth Group, 2018). Lack of access to primary care contributes to an increase in avoidable suffering and wasted dollars, as people are forced to seek expensive emergency care or hospitalization after their often preventable health condition is too advanced to ignore (Rosano et al., 2013; Shi, 2012). The primary care workforce is also changing. Between 2010 and 2016, the physician workforce grew by 1.1% whereas the nurse practitioner (NP) workforce grew by 9.4%; these trends are projected to continue through 2030, with the availability of advanced practice providers predicted to outstrip the availability of physicians in primary care (Auerbach, Staiger, & Buerhaus, 2018). Between 2008 and 2016, the fraction of providers who were NPs in primary care practices grew by over 40%, whereas the fraction of providers who were physicians in these settings dropped by 12% (Barnes, Richards, McHugh, & Martsolf, 2018). Given this shift, it is increasingly important to understand how statelevel NP scope of practice (SOP) policies influence access to primary care.