We find that 78.8% of counties exhibit a statistically significant relationship between total NOX emission density and the percentage of the population that is non-white (LDV 79.6%, MDV 78.9%, and HDV 74.2%). Similarly, 77.7% of counties demonstrate a statistically significant relationship between total NOX emission density and median household income (LDV 79.4%, MDV 79.2%, and HDV 71.8%). Similar patterns are observed for PM2.5 emission density, nonwhite population, and median household income. Furthermore, our analysis reveals a pervasive presence of higher TRAP emissions in areas where people of color and lower-income individuals reside. Figure illustrates that people of color and lower-income groups are disproportionately represented in regions with elevated emission density across the entire U.S., encompassing both urban and rural areas. This indicates that people of color and those with lower incomes face heightened exposure to NOX and PM2.5 vehicle traffic emissions across the nation.