Residential Mobility and the Reproduction of Environmental-Opportunity Inequality: Evidence from National Migration Flows and Multi-Pollutant Exposure, 2011–2019

Air pollution in the United States has decreased substantially, yet exposure remains unequal by race and ethnicity. Whether residential mobility narrows or widens this gap has been difficult to establish because nationwide mobility data have been limited. This study develops an exposure-reallocation estimand that measures, for households leaving each neighborhood, the flow-weighted difference between pollution at their destinations and origins. It applies the estimand to national block-group migration flows from 2011 to 2019 linked to eight pollutant surfaces. The aggregate decline in exposure reflected in-place cleanup rather than migration. Mobility nevertheless distributed those improvements unequally: conditional on origin pollution, movers from minority neighborhoods reached less clean destinations than comparable movers from white neighborhoods. The same qualitative pattern appears in individual census microdata. The disparity is little explained by destination housing values and exhibits a distinctive pollutant signature: largest for pollutants associated with fixed urban infrastructure, absent for wildfire smoke, and reversed for ozone. Over 2011 to 2019, these patterns are consistent with residential mobility reproducing environmental inequality.