Spatial Diversity (Part IV)

On Wednesday I explained how I quantified spatial diversity and then examined its relationship to participation, representation, and competition. Today, in my final post about my forthcoming article, I’ll discuss the empirical implications of my metric for race and redistricting.

In the racial context, it is not the spatial diversity of districts’ entire populations that matters, but rather the heterogeneity of their minority populations. In both the racial vote dilution and racial gerrymandering domains, the so-called “filler people” are irrelevant to the Court’s analysis. In order to analyze heavily minority districts, I therefore repeated the statistical procedure that I described on Wednesday, but only for Census tracts that are at least forty percent African-American or at least forty percent Hispanic. The end result was a single figure for each district that captures the geographic variation of its minority population with respect to a huge volume of Census information.

The first thing my data allowed me to do was to compare the spatial diversity of heavily minority districts to that of all districts (incorporating all Census tracts) nationwide. I found that the minority populations of heavily minority districts are somewhat more spatially varied, on average, than the whole populations of all of the country’s districts. However, the standard deviations of the minority distributions are substantially smaller and their right tails are not nearly as pronounced. This is evidence that most of the country’s worst gerrymandering (in the sense of very high spatial diversity) does not involve concentrated minority populations.

Second, I identified a series of heavily minority districts whose minority populations are particularly spatially varied. The Hispanic population of Florida’s Eighteenth District, for example, includes both very poor neighborhoods in downtown Miami and very affluent areas such as South Beach, Coral Gables, and Key Biscayne. Similarly, the African-American population of Maryland’s Fourth District encompasses both inner-ring suburbs of Washington, which resemble the city in their poverty and high proportion of renters, and prosperous outer-ring suburbs whose residents are mostly married home-owners.

Of course, this in no way proves that these districts are not required by the Voting Rights Act (let alone that they are racial gerrymanders). The districts’ minority residents may well feel a subjective sense of connection despite their socioeconomic differences. Geographic realities also may have made it difficult to design districts in these areas that contained more homogeneous minority populations. Nevertheless, evidence that a district’s minority population varies spatially in key respects is still quite probative. Even if it does not dispose of the issues, it at least suggests that the population is not compact and cohesive enough to warrant its own district under the VRA, and that race may have played a larger role than usual in the district’s creation.

Finally, I identified several heavily minority districts that are shaped very strangely but that are not troublesome at all from the standpoint of spatial diversity. Take Illinois’s well-known “earmuffs” district, for instance, which joins Hispanic communities in Chicago’s North and South Sides via a long and winding connector. Despite its bizarre shape, the district’s Hispanic population is actually very homogeneous, ranking thirty-fourth in geographic variation out of the country’s forty-three heavily Hispanic districts. So it should come as little surprise that courts twice held that the district was necessary under the VRA and constitutionally legitimate.

Similarly, North Carolina’s First District combines African-Americans throughout the northeastern part of the state, and features several odd-looking tentacles. But the district’s poor and rural African-American population is highly homogeneous, placing twenty-eighth in geographic variation out of the country’s thirty-one heavily black districts. This district too was upheld by the courts, with one judge noting that it is “a largely agrarian rural district” made up of areas that are “very high up on our economic tiers of depressed counties.”

As always, I’d be delighted to answer any questions that folks might have about my article. Thanks again to Rick for giving me the opportunity to share my findings. It’s been a pleasure.


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