REENA RAGGI, United States Circuit Judge, GERARD E.LYNCH, United States Circuit Judge, DORA L.IRIZARRY, United States District Judge:
This three-judge court was convened on February 14, 2012, pursuant to 28 U.S.C. § 2284(a), to address plaintiffs' complaint that defendants' failure to redraw New York's state and federal congressional districts consistent with the results of the 2010 Census deprives them of the ability to vote in upcoming elections in accordance with rights guaranteed by the federal and state constitutions, see U.S. Const. art. I, § 2; N.Y. Const. art. III, §§ 4, 5, and the Voting Rights Act of 1965, see 42 U.S.C. §§ 1973--1973aa-6.*fn1 Like the census that triggers it, this argument is now raised in federal courts at predictable ten-year intervals. See Rodriguez v. Pataki, No. 02-cv-618, 2002 WL 1058054 (S.D.N.Y. May 24, 2002); Puerto Rican Legal Def. & Educ. Fund, Inc. v. Gantt, 796 F. Supp. 681 (E.D.N.Y. 1992); Flateau v. Anderson, 537 F. Supp. 257 (S.D.N.Y. 1982). In the past, judicial creation of a congressional redistricting plan has spurred the New York legislature to produce its own plan just in time to avoid implementation of the judicial plan. See, e.g., Rodriguez v. Pataki, 308 F. Supp. 2d 346, 357--58 (S.D.N.Y.) (describing state legislature's enactment of congressional redistricting plan shortly after court adoption of special master plan), aff'd, 125 S. Ct. 627 (2004). This time is different. With less than 24 hours until the scheduled March 20, 2012 start of the petitioning process for theJune 26, 2012congressional primaries, the New York legislature has not delineated congressional districts for the state. Accordingly, the court declares New York to be without a congressional redistricting plan that conforms to the requirements of federal law, and it hereby orders defendants to implement the redistricting plan attached as Appendix 1 to this opinion ("Ordered Plan").*fn2
I. The Undisputed Merits of Plaintiffs' Claim That New York Lacks a Constitutional Congressional Redistricting Plan
Defendants do not seriously dispute plaintiffs' claim that New York is without a constitutional congressional redistricting plan for the 2012 elections.*fn3 Nor could they. As a result of the relative decline in New York's population reflected in the 2010 Census, the number of congressional districts allotted to the state is reduced from 29 to 27. See Kristin D. Burnett, U.S. Census Bureau, 2010 Census Briefs: Congressional Apportionment 2 (Nov. 2011), available at http://www.census.gov/prod/cen2010/briefs/c2010br-08.pdf; see generally U.S. Const. art. I, § 2, cl. 3; 2 U.S.C. § 2a. Thus, New York cannot operate under its existing congressional districting plan. Rather, it must redraw congressional district lines in order to have representatives seated in the 113th Congress.*fn4 Further, the state must do so in a way that both (1) conforms to the constitutional mandate that "as nearly as is practicable one man's vote in a congressional election is to be worth as much as another's," Wesberry v. Sanders, 376 U.S. 1, 7--8 (1964), and (2) adheres to the constitutional prohibition against both intentional and excessive uses of race or ethnicity in redistricting, see Miller v. Johnson, 515 U.S. 900, 916 (1995) (prohibiting use of race or ethnicity as "predominant factor" motivating decision to place significant number of voters within or without particular district); City of Mobile v. Bolden, 446 U.S. 55, 66 (1980) (holding that redistricting cannot purposefully discriminate against racial group by diluting its vote). Federal law also obligates New York to effect redistricting consistent with the Voting Rights Act,particularly Section 2, which ensures against minority vote dilution, see 42 U.S.C. § 1973, and Section 5, which forbids retrogression in the electoral position of minorities in covered jurisdictions, see id. § 1973c, here including New York, Kings, and Bronx Counties, see 28 C.F.R., pt. 51, App.
No such plan being in place, plaintiffs are entitled to both a declaratory judgment in their favor and relief in the form of a judicially ordered congressional redistricting plan.
II. The Ordered Redistricting Plan
In ordering defendants to implement the attached redistricting plan, we adopt the March 12, 2012 Report of Magistrate Judge Roanne L. Mann in its entirety and the redistricting plan recommended therein, see Report and Recommendation (Mar. 12, 2012), Dkt. Entry 223 ("Report" or "Recommended Plan"). The court's Ordered Plan modifies the Recommended Plan only to the extent noted in the margin.*fn5 We write here to discuss the process and legal principles informing development of the Ordered Plan, and the court's reasons for rejecting certain objections or complaints about the Recommended Plan from parties and interested members of the public.
A. The Process Employed To Develop the Ordered Plan
1. Defendants' Ripeness Challenge
Rather than challenge the merits of plaintiffs' claim before the three-judge panel or the magistrate judge, defendants questioned its ripeness, moving for dismissal on the ground that state inaction had not yet reached the point where a court could recognize a violation of federal law. We rejected this argument in an electronic order on February 21, 2012, supported by an opinion filed on March 8, 2012. See Order Denying Motions to Dismiss (Mar. 8, 2012), Dkt. Entry 219.*fn6 With the petitioning process for the state's congressional elections set to begin on March 20, 2012, and with defendants conceding that no new congressional district plan was imminent, plaintiffs' claim was plainly ripe.*fn7 Not only did the existing plan-providing for 29 congressional districts that do not comport with either the 2010 Census or the constitutional mandate of "one person, one vote"-clearly violate federal law, but also the court's ability to provide the necessary remedy, a constitutional redistricting plan, in time for the March 20 petitioning process faced significant time challenges. See id. at 7--14.*fn8
2. The Magistrate Judge's Report
In order to provide a timely remedy, on February 27, the court referred the task of devising a recommended plan for redrawing New York's congressional districts to Magistrate Judge Mann with instructions to issue a report and recommendation to the court on March 12, 2012.*fn9 The court further authorized the retention of Dr. Nathaniel Persily as a redistricting expert to assist Magistrate Judge Mann and this court in fashioning redistricting relief.*fn10 See Order of Referral to Magistrate Judge at 3--4 (Feb. 28, 2012), Dkt. Entry 133.
Exerting efforts that have been aptly characterized as "Herculean,"*fn11 Magistrate Judge Mann filed a detailed report and plan recommendation on March 12, supported by Dr. Persily's equally detailed affidavit and accompanying exhibits. The Report is remarkable in several respects. First, and most obviously, it provides this court in two weeks' time with what defendants have been unable-or unwilling-to provide New York State voters in more than a year: a redistricting plan for the state's congressional districts. In doing so, the Report cogently sets forth controlling principles of law, the challenging choices implicated in any redistricting assignment, and the magistrate judge's reasons for making the choices reflected in the Recommended Plan. Second, the Report discusses the commendable process employed by the magistrate judge to develop the Recommended Plan, which afforded the parties and interested members of the public frequent opportunities to be heard. See Report at 8--12. Third, the Report recommends a redistricting plan that is exemplary in satisfying each and every standard set forth in this court's referral order.
3. Adoption of the Report and Recommended Plan
This court is nevertheless required to review the Recommended Plan de novo and to decide for itself what redistricting plan is necessary to ensure compliance with controlling law. See 28 U.S.C. § 636(b)(1); Fed. R. Civ. P. 53(f). Toward that end, we have carefully reviewed not only the magistrate judge's Report and Recommended Plan, but also all filings in the case, including all submitted plans (partial or statewide),*fn12 as well as all objections and comments to the Recommended Plan presented by any party or interested person either in writing or at a public hearing conducted on March 15, 2012.*fn13 The court has consulted further with Dr. Persily to ensure its full understanding of the demographics informing the Recommended Plan and implicated in changes urged by the parties or members of the public. Upon such careful and independent review, we adopt the magistrate judge's Report and Recommended Plan, with only minor and uncontroversial adjustments as indicated supra note 5.
4. Legal Principles Informing the Court's Decision In ordering defendants to implement the court's redistricting plan, we are guided by principles of law that all parties agree are accurately set forth in the magistrate judge's Report. See Report at 13--19 (discussing constitutional and statutory redistricting standards);
id. at 21--38 (discussing traditional redistricting factors). Because we adopt the Report, we do not repeat that discussion here. Nevertheless, in light of apparent confusion by some parties and members of the public at the March 15, 2012 hearing as to the court's obligations with respect to redistricting principles that impose legal mandates as compared with principles that afford some discretion, a preliminary discussion is useful to our subsequent analysis of specific objections.
a. The Constitutional Mandate of "One Person, One Vote"
At the first tier of redistricting analysis, the controlling principle is constitutional and mandatory: Article I, Section 2 requires that congressional election districts conform to the principle of "one person, one vote." Abrams v. Johnson, 521 U.S. 74, 98 (1997); Wesberry v. Sanders, 376 U.S. 1, 7--8 (1964); see also Reynolds v. Sims, 377 U.S. 533, 561--64, 568 (1964) (holding that state election districts must be apportioned by equal population).To satisfy this mandate, the population of each of New York's 27 new congressional districts must be within one person of the target number of 717,707 persons. See Report at 14; Aff. of Professor Nathaniel Persily, J.D., Ph.D. ¶¶ 103--04 (Mar. 12, 2008), Dkt. Entry 223, Attach. 1 ("Persily Aff."); see also Abrams v. Johnson, 521 U.S. at 98 (holding that "[a] court-ordered plan should ordinarily achieve the goal of population equality with little more than de minimis variation" (internal quotation marks omitted)). Thus, in considering arguments urging that persons be moved from one district to another in furtherance of one or more of the traditional redistricting factors discussed infra Part II.A.4.c, this court is constitutionally mandated to replace any persons moved with the same number of persons drawn from another district. As should be obvious, this means that, with the exception of changes that can be effected with a simple population swap between two districts, see, e.g., supra n.5 (discussing some such population swaps), most changes will trigger a ripple effect through multiple districts with serious constitutional implications for the entire redistricting plan.
b. Constitutional and Statutory Prohibition of Discriminatory Redistricting
The second tier of redistricting analysis is of equal importance to the first in that it too is constitutional and mandatory: a redistricting plan cannot intentionally discriminate against a racial or ethnic group. See City of Mobile v. Bolden, 446 U.S. at 66; White v. Regester, 412 U.S. 755, 765--66 (1973); Gomillion v. Lightfoot, 364 U.S. 339, 341--42, 346 (1960). At the same time, race or ethnicity cannot be used as the "predominant factor" in deciding whether to put significant numbers of persons within or without a particular district. Miller v. Johnson, 515 U.S. at 916; see Shaw v. Reno, 509 U.S. 630, 642--49 (1993). The prohibition on discrimination is reinforced by the Voting Rights Act, which proscribes both minority vote dilution in Section 2, see 42 U.S.C. § 1973, and retrogression of existing minority strength in jurisdictions covered under Section 5, see id. § 1973c. Magistrate Judge Mann accurately discusses in some detail the law relevant to these principles, and thus, we do not repeat that discussion here. See Report at 13--19; see also Rodriguez v. Pataki, 2002 WL 1058054, at *4 (setting forth same legal standards in reviewing special master plan for 2002 New York redistricting). Further, the appendices attached to Dr. Persily's affidavit document the care taken in the Recommended Plan-and, now, the Ordered Plan-to safeguard against minority vote dilution and retrogression. See Persily Aff., Apps. A--J. Here too, then, we consider arguments urging this court to move persons from one district to another mindful of our obligation not to make any changes that could cause vote dilution or retrogression.
c. Traditional Redistricting Factors
At the third tier of redistricting analysis, a court considers, to the extent possible, traditional principles that generally inform legislative redistricting. This process contemplates the exercise of discretion.
In our referral to the magistrate judge, this court identified four traditional redistricting factors warranting consideration: (1) district compactness, (2) contiguity, (3) respect for political subdivisions, and (4) preservation of communities of interest.SeeOrder of Referral to Magistrate Judge at 3 (Feb. 28, 2012), Dkt. Entry 133.At the same time, we stated that the magistrate judge's discretion to weigh these factors also extended to other factors that she might identify as reasonable, consistent with otherwise controlling law. See id. Two further traditional redistricting factors urged by the parties and members of the public are (5) maintaining the cores of existing districts and (6) protecting incumbency.*fn14 See Karcher v. Daggett, 462 U.S. 725, 740 (1983) (recognizing these two factors as traditional considerations in legislative redistricting); Diaz v. Silver, 978 F. Supp. 96, 105, 123 (E.D.N.Y.) (stating that maintaining cores of existing districts is traditional redistricting factor, and that it is not improper for legislature to consider incumbency in enacting redistricting plan), aff'd, 522 U.S. 801 (1997).
In fact, the magistrate judge's Report carefully addresses each of these six factors, discussing both the factor's relevancy to redistricting and the concerns associated with its application. See Report at 21--38. The magistrate judge accords some weight to each of these factors, with the single exception of incumbency protection. See id. In all respects pertaining to traditional redistricting factors, we adopt both the Report's reasoning and its conclusions as our own. We add only a few observations relevant to our future discussion of particular objections to the weight assigned to some of the traditional factors. These demonstrate that the noted traditional factors are not all of a kind.
First, only the first three traditional redistricting factors-compactness, contiguity, and respect for political subdivisions-can claim the sanction of enacted New York law. The State Constitution requires that State Senate and Assembly districts be contiguous and "in as compact form as practicable."N.Y. Const. art. III, §§ 4, 5 (emphasis added). It further requires that such districts consist of contiguous territory, andlimits the division of counties, towns, and city blocks in forming state legislative districts. See id. Where state policy is thus reflected in law, there is sound reason for a court to accord that policy some weight, even when devising a redistricting plan for the federal rather than state legislature, subject, of course, to the superior demands of federal law, see U.S. Const. art. VI, cl. 2. As detailed in the magistrate judge's Report, the Recommended Plan is scrupulous in ensuring district contiguity; further, it achieves compactness and avoids splitting political subdivisions better than the existing plan. SeeReport at 23--24 (noting that Recommended Plan achieves compactness and contiguity in all districts, and splits six fewer counties and five fewer towns than existing plan); Persily Aff. ¶¶ 134--35 (stating that Recommended Plan keeps together 42 of 62 counties, and 894 of 970 towns, both of which improve on existing congressional districts). Indeed, the Ordered Plan has itself modified the Recommended Plan to unite one more county and three more towns, changes that could be effected without undue disruption to the overall plan's compliance with federal law. See supra n. 5. Thus, the Recommended Plan keeps 43 New York counties and 897 towns whole.
Second, the remaining factor identified in our referral order, the preservation of communities of interest, has no comparable pedigree in enacted state law. While the preservation of communities of interest has been recognized as "a legitimate goal in creating a district plan," Diaz v. Silver, 978 F. Supp. at 123, we observe, as did the magistrate judge, that this factor can more easily draw the court into political debates than factors such as compactness, contiguity, and respect for political subdivisions. These last three factors are more susceptible to neutral analysis, with a court's options and choices often evident on a map.*fn15 But the identification of a "community of interest," a necessary first step to "preservation," requires insights that cannot be obtained from maps or even census figures. Such insights require an understanding of the community at issue, which can often be acquired only through direct and extensive experience with the day-to-day lives of an area's residents. Legislators are expected to have such understanding and experience. Judges are not. Thus, even if legislators routinely seek to preserve their constituents' communities of interest in a new redistricting plan, ...