Table 1 depicts the population-weighted average exposure to flooding for different racial/ethnic groups for the contiguous U.S. and individual states. For the nation as a whole, the average person’s chance of experiencing a flood in any given year is one-in-ten. These exposure probabilities range from a low of .045 (about one-in-twenty) in Arizona to a high of .249 (one-in-four) in Louisiana. While the majority of variation is between states, we also see substantial variation among racial/ethnic groups within states. Employing the mean exposure of Whites in that state as baseline, we sequentially test whether the mean exposure of each racial/ethnic group differs from that baseline. For ease of interpreting Table 1, we shade in dark grey instances where the minority group has a statistically significantly higher mean and in light grey the instances where the minority group has a statistically significantly lower mean, compared to Whites’.
Despite a large body of environmental justice literature suggesting that traditionally disadvantaged minority groups, especially Blacks, are disproportionally exposed to environmental hazards, we observe no states in which non-Hispanic Blacks have a (statistically) significantly higher average exposure to floods than non-Hispanic Whites (Table 1). Even more surprising, Blacks have significantly lower exposure to floods than non-Hispanic Whites in 21 states. This general finding of there being no states with a significantly higher relative exposure but several states with significantly lower relative exposure extends to other non-White racial groups, including non-Hispanic Asians, non-Hispanic Pacific Islanders/Others, and non-Hispanic individuals of two or more races.
Inequalities in flood exposure between (non-Hispanic) Whites and Hispanics of any race exhibit a mixed pattern, with Hispanics having a significantly higher average exposure in three states, and a significantly lower average exposure in 18 states. Notably, however, the aggregate Hispanic population of the three states where Hispanics face greater flood exposure (Illinois, Massachusetts, and Texas) exceeds the aggregate Hispanic population of the 18 where their average exposures are lower than Whites’.
Flood exposure inequalities between non-Hispanic Whites and Native Americans exhibit large differences from those of other minority groups. We find no states in which Native Americans have a significantly lower average exposure to floods than non-Hispanic Whites, but eight states in which Native Americans have significantly higher exposure. Notably, this set of states includes four of the eight states with the largest Native American populations: California, Arizona, Washington, and North Carolina. In aggregate, the Native American population in the eight states with significant exposure differences accounts for 31% of the entire Native American population in the US. This finding constitutes a sizable disparity that we believe has been neglected in the distributive environmental justice literature.
Prior research has suggested that interracial disparities in flood exposures may differ between coastal and inland areas (Chakraborty et al. 2014; Montgomery and Chakraborty, 2015; Qiang et al., 2017). As such, we present results looking at intersections of state, racial/ethnic group, and coastal/inland census tract status in Tables 2 and 3 and Figs. <link rid="fig1">1</link> and 1. Unsurprisingly, for the population in the contiguous U.S. as a whole, average annual flood exposure is much lower in inland (.090) than coastal (.226) areas. These results also generally indicate that more interracial disparities exist among inland tracts than among coastal tracts. This is expected, given the widespread observation (e.g., Maantay and Maaroko 2009; Montgomery and Chakraborty 2015; Ilbeigi and Jagupilla 2020) that higher-income Whites often willingly assume greater coastal flood exposures for the compensating amenity benefits associated with such locations. As illustration, Native Americans in inland neighborhoods face statistically significantly higher average flood exposures than Whites nationally and in eight states, but this pattern is replicated for coastal areas in only two states (Louisiana and Washington). Hispanics represent a partial exception to this pattern, inasmuch as they evince significantly higher exposures than Whites nationally in coastal ones but not inland ones, though this result is heavily driven by the only state with a significant difference in coastal areas: Florida. Nevertheless, in inland areas of five states the average exposures of Hispanics are significantly higher than Whites’.
Inter-state patterns among racial/ethnic groups generally follow for inland tracts as they do for all tracts (given their preponderance in the sample), with some exceptions. First, in Texas inland tracts we observe that Blacks and Asians have significantly higher average flood exposures than Whites. This is notable since Texas has the largest Black population and the third-largest Asian population of any state in the US.
Second, while we observed no overall statistically significant difference in flood exposure between Hispanics and Whites in Florida, differences do emerge once we stratify by coastal and inland status. In both cases, Hispanics have significantly greater exposure than Whites. The importance of this finding is two-fold. First, Florida has the third-largest Hispanic population of any state in the US. Second, the coastal and inland overall flood exposures in Florida are already the second-highest in the nation. The stratification of flood exposure by coastal and inland tracts thus reveals an otherwise-masked interracial disparity that is substantive both in the magnitude of difference and the number of minorities affected.
Finally, stratification between coastal and inland tracts reveals several miscellaneous racial disparities not revealed in aggregating the two types. We find that Hispanics in New Jersey have a significantly higher flood exposure compared to Whites, but only in inland census tracts. Additionally, we find Pacific Islander/Other individuals have significantly higher flood exposure compared to Whites in coastal tracts in California.