Contains historical and current data on the US physician population. Compiled from the AMA Physician Masterfile, it is the most accurate information available today for the physician market. Data is obtained from AMA surveys and input from physicians, as well as other organizations and institutions. PCD provides basis for comparison essential for health services research, program planning, and policy development. Data is presented in three key sections. Trends provide data on major professional activity, specialties, age, gender and population ratios by nation, state and specialty. Characteristics presents key professional and individual characteristics of the physician population by age and gender, including country, year and school of graduation, specialties, and board certification. Distribution shows census summary data by state, age and gender, as well as specialty and activity by location, non-federal physicians, and medical practice data.