A United States cohort study is a type of research study that follows a group of individuals over a long period of time to gather data on various health outcomes and risk factors. These studies can provide valuable information on the causes and prevention of diseases, as well as the effectiveness of treatments and interventions. Cohort studies in the United States often involve large groups of participants from diverse backgrounds, allowing researchers to draw more generalizable conclusions about health and well-being in the population. Participants are typically recruited based on certain characteristics or behaviors, such as age, occupation, or health status, and are followed over a specified period of time to track changes in their health and lifestyle factors.