Cite as: 602 U. S. ____ (2024) 21 KAGAN, J., dissenting attached to the opposite finding—that Roberts put this hugely relevant data on his screen only to ignore it as he worked to make District 1 more Republican. That would have taken the self-restraint of a monk. Especially so because using only the political data at hand would not have done the job as well. “Why,” the majority asks, “would Roberts have used racial data” when he had access to sub-precinct-level voting data from the 2020 election? Ante, at 18; see ante, at 33–34. The question is apparently meant to be rhetorical; but the trial record provides a ready answer—and one more than sufficient on clear-error review. One of the Challengers’ experts testified that “[t]he 2020 election data” was “not a good” measure of partisan tilt—neither so “accurate” nor so “reliable.” App. 135. And racial data, another expert suggested, served the mapmakers’ goal better. See id., at 112. The single-sentence explanation is this: In South Carolina, a Black voter is more likely to vote for a Democrat in the next election than is someone who voted for a Democrat in the last election. That is because White voting preferences in the State are not as “stable” as Black voting preferences. Ibid. A White voter “might vote for a Democrat in one election” only to vote “for a Republican in another.” Ibid. So to remove a past Democratic voter (as contrasted with a Black voter) is not necessarily to remove a future Democratic vote. 5 And the gap only widens for past presidential voters, like those who participated in the 2020 election. In presidential elections, one expert explained, more people than usual switch party lines to “vote for the candidate”—a trend that thenPresident Trump’s candidacy may have further amplified. Id., at 135; see J. S. A. 382a. Given all that, the South Carolina mapmakers’ racial data was peculiarly predictive: The —————— 5 The same variability occurs the other way around. In other words, a White voter might vote for a Republican in one election only to vote for a Democrat in another. So to retain a past Republican voter in a district is not necessarily to retain a future Republican vote.

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