Other ; The National Health and Nutrition Examination Survey (NHANES) is an epidemiological survey implemented by the Centers for Disease Control and Prevention (CDC) to monitor the health of a representative population of the United States. While publicly available, analysts need to spend a significant amount of time merging and stitching together numerous separate and proprietary formatted data files to incorporate the data in their research. This Data Descriptor describes a single unified and universally accessible data file, merging across 251 separate files and stitching data across 4 surveys, encompassing 41,474 individuals and 1191 variables. The variables consist of phenotype and environmental exposure information on each individual, specifically (1) demographic information, physical exam results (e.g., height, body mass index), laboratory results (e.g., cholesterol, glucose, and environmental exposures), and (4) questionnaire items. Second, the data descriptor describes a dictionary to enable analysts find variables by category and human-readable description. The datasets are available in .csv and .Rdata format.