Figure illustrates the geographic distribution of NOX and PM2.5 census block emission densities across the United States in 2020, categorized by type of vehicle traffic. The data reveal substantial variations in average daily vehicle emissions nationwide, particularly highlighting significant emissions from truck traffic in certain regions. Specifically, the map delineates distinct patterns in NOX and PM2.5 emissions originating from LDV, MDV, and HDV traffic across the U.S. Emissions from LDVs are concentrated in urban areas, reflecting higher population densities and greater vehicle usage. Conversely, MDV and HDV emissions are more dispersed, prominently extending along interstate highways and arterial roads outside urban centers. These diverse emission patterns underscore the necessity of separately evaluating LDV, MDV, and HDV traffic emissions due to both their differing emission rates and spatial distributions. To provide a comprehensive assessment, we calculate the population-weighted mean average daily census block emission density, referred to as average emissions exposure, across various geographic scales, including counties and nationwide.