Cite as: 602 U. S. ____ (2024) 23 Opinion of the Court Using this approach, he first identified the five counties that have at least one precinct that fell within District 1 in the Benchmark Plan. These counties in their entirety constituted the “county envelope.” Dr. Ragusa employed a method that we will discuss below to control for the partisan preferences of voters in these precincts, and he also controlled for precinct size. He then asked whether a precinct of a given size with a given partisan breakdown was more or less likely to be included in District 1 depending on its racial demographics, and he reported that districts with a high percentage of black voters were more likely to be excluded. His remaining model looked only at the precincts that were in District 1 in the Benchmark Plan, and controlling in the same way for size and partisan leaning, he reported that a precinct was more likely to be moved out if it had a high percentage of black voters. All three of these models exhibit the same flaw. Because they did not control for contiguity or compactness, they all assume that a precinct could be moved into or out of District 1 regardless of its distance from the line between that district and District 6. That is highly unrealistic. A simple example illustrates this point in relation to the county envelope approach, as can be seen with a quick look at Figure 1, which we again reproduce below.

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