Cite as: 588 U. S. ____ (2019) 23 KAGAN, J., dissenting characteristics and judgments. The effects evidence in these cases accepted as a given the State’s physical geography (e.g., where does the Chesapeake run?) and political geography (e.g., where do the Democrats live on top of each other?). So the courts did not, in the majority’s words, try to “counteract ‘natural’ gerrymandering caused, for example, by the urban concentration of one party.” Ante, at 19. Still more, the courts’ analyses used the State’s own criteria for electoral fairness—except for naked partisan gain. Under their approach, in other words, the State selected its own fairness baseline in the form of its other districting criteria. All the courts did was determine how far the State had gone off that track because of its politicians’ effort to entrench themselves in office. The North Carolina litigation well illustrates the point. The thousands of randomly generated maps I’ve mentioned formed the core of the plaintiffs’ case that the North Carolina plan was an “extreme[ ] outlier.” Rucho, 318 F. Supp. 3d, at 852 (internal quotation marks omitted); see supra, at 18–20. Those maps took the State’s political landscape as a given. In North Carolina, for example, Democratic voters are highly concentrated in cities. That fact was built into all the maps; it became part of the baseline. See Rucho, 318 F. Supp. 3d, at 896–897. On top of that, the maps took the State’s legal landscape as a given. They incorporated the State’s districting priorities, excluding partisanship. So in North Carolina, for example, all the maps adhered to the traditional criteria of contiguity and compactness. See supra, at 19–20. But the comparator maps in another State would have incorporated different objectives—say, the emphasis Arizona places on competitive districts or the requirement Iowa imposes that counties remain whole. See Brief for Mathematicians et al. as Amici Curiae 19–20. The point is that the assemblage of maps, reflecting the characteristics and