Recent research on how to reduce air pollution exposure disparities in the U.S. presents two conflicting approaches . The first approach starts from the recognition that many major emitting sectors lead to disparate exposures for people of color . Thus, focusing on emissions reductions for sectors that especially impact people of color could have EJ cobenefits . This approach mirrors the policy structure in the U.S. and elsewhere, where environmental regulations are targeted to individual economic sectors (e.g., vehicles, industries, power plants) and tailored to relevant technology and infrastructure. The second body of research suggests that sector-oriented policies may not be effective in addressing relative disparities in air pollution. For example, optimization modeling found that aggressive nationwide emissions reductions targeting economic sectors with higher-than-average disparity impact would not eliminate racial-ethnic fine particulate matter (PM2.5) exposure disparities without nearly eliminating emissions . In contrast, a location-specific approach -i.e., emissions-reductions by location rather than by economic sector -rapidly eliminated disparities. Building upon this finding, two recent studies simulated climate policies with substantial abatement of PM2.5 and its precursors across most U.S. economic sectors and found modest potential reductions in disparities. They too reported that "location-specific" policies that target emissions reductions in all sectors within specific overburdened geographies may have high potential to address relative exposure disparities even with small emissions changes . To complement prospective studies, which consider ways to reduce future exposure disparity, we examine the disparity impacts of historical emissions trajectories. We focus on the transportation sector, which is often highlighted as having high potential to reduce exposure disparities. Historically, racist urban planning and infrastructure decisions (e.g., redlining, freeway siting) have concentrated vehicle emissions in communities of color . Furthermore, people who are exposed to the highest levels of traffic-related air pollution often are not the communities who drive the most . As such, a recent study found that emissions controls for the transportation sector have the greatest potential to mitigate racial-ethnic inequality in U.S. air pollution . Simultaneously, the transportation sector is a priority area for regulatory agencies and EJ-oriented community groups; emissions reductions from these sources could potentially reduce exposure disparities, human health impacts, and greenhouse gas emissions .