The first dose reconstruction and cancer risk projection for the population of New Mexico as a consequence of exposure to radioactive fallout from the Trinity nuclear test was published in 2020. This comprehensive evaluation was conducted by investigators from the National Cancer Institute (NCI) with collaborators over a 7-year time period. This technical note primarily summarizes the already published design considerations of that study, the methods of data collection, study limitations, and findings, though it also summarizes important events that took place over several decades that led to the NCI Trinity study. In addition, we discuss two related investigations that were part of the NCI Trinity study: the possibility of intergenerational (genetic) effects among those exposed and an analysis of the whereabouts, quantity, and health implications of the unfissioned plutonium from Trinity. Finally, we provide doses received by the military and civilian participants in the Trinity test as reported by other organizations.