PA scope of practice reform: History informing the future.

State-level physician associate/assistant (PA) practice regulations have evolved since the profession's inception. The conditions that influence states' adoption of PA regulatory reforms are not fully understood. As some states begin to adopt components of optimal team practice, PAs in other states continue to face significant legal and regulatory practice restrictions. This article describes state economic, demographic, and workforce characteristics and highlights important differences across states that may affect future reform adoption and shape reform outcomes.