Importance: The current state of the US pathologist workforce is uncertain, with deficits forecast over the next 2 decades. Objective: To examine the trends in the US pathology workforce from 2007 to 2017. Design, Setting, and Participants: A cross-sectional study was conducted comparing the number of US and Canadian physicians from 2007 to 2017 with a focus on pathologists, radiologists, and anesthesiologists. For the United States, the number of physicians was examined at the state population level with a focus on pathologists. New cancer diagnoses per pathologist were compared between the United States and Canada. These data from the American Association of Medical Colleges Center for Workforce Studies' Physician Specialty Data Books and the Canadian Medical Association Masterfile were analyzed from January 4, 2019, through March 26, 2019. Main Outcomes and Measures: Numbers of pathologists were compared with overall physician numbers as well as numbers of radiologists and anesthesiologists in the United States and Canada. Results: Between 2007 and 2017, the number of active pathologists in the United States decreased from 15 568 to 12 839 (-17.53%). In contrast, Canadian data showed an increase from 1467 to 1767 pathologists during the same period (+20.45%). When adjusted for each country's population, the number of pathologists per 100 000 population showed a decline from 5.16 to 3.94 in the United States and an increase from 4.46 to 4.81 in Canada. As a percentage of total US physicians, pathologists have decreased from 2.03% in 2007 to 1.43% in 2017. The distribution of US pathologists varied widely by state; per 100 000 population, Idaho had the fewest (1.37) and the District of Columbia had the most (15.71). When adjusted by new cancer cases per year, the diagnostic workload per US pathologist has risen by 41.73%; during the same period, the Canadian diagnostic workload increased by 7.06%. Conclusions and Relevance: The US pathologist workforce decreased in both absolute and population-adjusted numbers from 2007 to 2017. The current trends suggest a shortage of US pathologists.