opinion: Justice White
  delivered the opinion of the Court.
  Section 5 of the Voting Rights Act of 1965, 79 Stat. 439, as amended, 42 U. S. C. § 1973c, requires that when a State or political subdivision covered by the Act adopts or seeks to administer any change in its standards, practices, or procedures with respect to voting, it must obtain a preclearance either from the Attorney General of the United States or by obtaining a declaratory judgment from the District Court for the District of Columbia that the proposed change has neither the purpose nor the effect of denying or abridging the right to vote on account of race. Perkins v. Matthews, 400 U. S. 379 (1971), held that changes in the boundary lines of a city by annexations that enlarge the number of eligible voters are events covered by §5. The question in this case is whether the District Court for the District of Columbia correctly held that the electoral plan for the Port Arthur, Tex., City Council could not be approved under § 5 because it insufficiently neutralized the adverse impact upon minority voting strength that resulted from the expansion of the city’s borders by two consolidations and an annexation.
  H — (
  In December 1977, the city of Port Arthur, Tex., consolidated with the neighboring cities of Pear Ridge and Lake View. Six months later, the city annexed Sabine Pass, an incorporated area. As a result of these expansions of the city's borders, the percentage of the black population in Port Arthur decreased from 45.21% to 40.56%. Blacks of voting age constituted 35% of the population of the enlarged city.
  Prior to the expansions, the city was governed by a seven-member Council, including a mayor, each member being elected at large by majority vote. Each member except the mayor was required to reside in a specific district of the city. Members were elected for staggered terms. Following the two consolidations, the City Council passed an ordinance adding an eighth member to the Council, while retaining the at-large system with residency requirements. After the annexation of Sabine Pass, the city further proposed that the Council be expanded to nine members, with at-large elections as before. The two consolidations and the annexation, together with the proposed changes in the governing system, were submitted to the Attorney General for preclearance pursuant to §5 of the Voting Rights Act. The Attorney General refused preclearance, suggesting, however, that he would reconsider if the Council members were elected from fairly drawn single-member districts.
  As §5 permitted it to do, the city then filed suit in the United States District Court for the District of Columbia seeking a declaratory judgment that the expansions and the nine-member plan did not have the purpose or effect of denying or abridging the right to vote on account of color or race within the meaning of § 5. While that suit was pending, the city approved by referendum the “4-4-1” plan, calling for four members to be elected from single-member districts, four to be elected at large from residency districts identical to the single-member districts, and the ninth member, the mayor, to be elected at large without any residency requirement. That plan, like the previous plans, required a majority vote to elect each Council member. The city then moved to amend its complaint so as to seek a declaratory judgment as to the legality of the 4-4r-l plan.
  The District Court concluded that because there were legitimate purposes behind the annexation and the consolidations, those actions, under City of Richmond v. United States, 422 U. S. 358 (1975), could not be denied preclearance as discriminatory in purpose. 517 F. Supp. 987 (1981). Because the expansions had substantially reduced the relative political strength of the black population, however, it was necessary for preclearance that the postexpansion electoral system be found to satisfy the requirements of § 5. The District Court held that neither the first nine-member plan nor the 4-4-1 plan measured up, not only because each was adopted, with a discriminatory purpose, but also because in the context of the severe racial bloc voting characteristic of the recent past in the city neither plan adequately reflected the minority’s potential political strength in the enlarged community as required under City of Rome v. United States, 446 U. S. 156 (1980); City of Richmond v. United States, supra; and City of Petersburg v. United States, 354 F. Supp. 1021 (DC 1972), summarily aff’d, 410 U. S. 962 (1973).
  Soon after this decision, the city and the United States jointly submitted to the court for approval the “4-2-3” electoral plan. Under this scheme, the city would be divided into four single-member districts, Districts 1 through 4. District 5, comprising Districts 1 and 4 would elect another member, as would District 6, which combined Districts 2 and 3. Three additional members would be elected at large, one each from Districts 5 and 6, the third at-large seat to be occupied by the mayor and to have no residency requirement. All Council seats would be governed by the majority-vote rule, that is, runoffs would be required if none of the candidates voted on received a majority of the votes cast. Blacks constituted a majority in Districts 1 and 4, 79% and 62.78% respectively, as well as a 70.83% majority of the fifth district combining the two majority black districts. The sixth district was 10.98% black. Although the United States expressed reservations about the at-large and majority-vote features, its position was that neither of these aspects of the plan warranted a denial of preclearance.
  After response to and oral argument upon the submission, the District Court concluded “that the proposed plan insufficiently neutralizes the adverse impact upon minority voting strength which resulted from the expansion of Port Arthur’s borders.” App. 87a. The court added, however, that if the plan were modified to eliminate the majority-vote requirement with respect to the two nonmayoral, at-large candidates, and to permit election to these two seats to be made by a plurality vote, the court “would consider the defect remedied and offer our approval.” Id., at 87a-88a. This appeal followed, the basic submission being that under § 5 and the controlling cases the District Court exceeded its authority in conditioning clearance of the 4-2-3 plan on the elimination of the majority-vote requirement. We noted probable jurisdiction. 455 U. S. 917 (1982).
  M HH
  Perkins v. Matthews, 400 U. S. 379 (1971), held that annexations by a city are subject to § 5 preclearance because increasing the number of eligible voters dilutes the weight of the votes of those to whom the franchise was limited before the annexation and because the right to vote may be denied by dilution or debasement just as effectively as by wholly prohibiting the franchise. It soon became clear, however, that § 5 was not intended to forbid all expansions of municipal borders that could be said to have diluted the voting power of particular groups in the community. In City of Petersburg v. United States, supra, the annexation of an area with a heavy white majority resulted in reducing the black community from majority to minority status. The District Court held that the annexation could nevertheless be approved but “only on the condition that modifications [in the electoral plan] calculated to neutralize to the extent possible any adverse effect upon the political participation of black voters are adopted, i. e., that the [city] shift from an at-large to a ward system of electing its city councilmen.” 354 F. Supp., at 1031. We affirmed summarily. 410 U. S. 962 (1973).
  Later, in City of Richmond v. United States, supra, we expressly reaffirmed Petersburg, recognizing that the Peters-burg annexation enhanced the power of the white majority to exclude Negroes from the city council but stating that such a consequence “would be satisfactorily obviated if at-large elections were replaced by a ward system of choosing councilmen.” 422 U. S., at 370. It was our view that a fairly designed ward plan “would not only prevent the total exclusion of Negroes from membership on the council but would afford them representation reasonably equivalent to their political strength in the enlarged community.” Ibid. We applied these principles in City of Richmond. There, the annexation of a heavily white area reduced the black population of the city from 52% to 42%, and the electoral proposal submitted for preclearance replaced the prior system of at-large elections with a single-member plan under which blacks would be in a substantial majority in four of the nine councilmanic districts. We held that as long as the ward system fairly reflected the strength of the Negro community as it existed after the annexation, preclearance under §5 should be granted. Under such a plan, “Negro power in the new city [would not be] undervalued, and Negroes [would] not be underrepresented on the council.” Id., at 371. The annexation could not, therefore, be said to have the effect of denying or abridging the right to vote on account of race within the meaning of § 5.
  In the case before us, Port Arthur was a party to two consolidations and an annexation. Because the areas taken into the city were predominantly white, the relative percentage of blacks in the enlarged city was substantially less than it was before the expansions. The District Court refused preclearance because in its view the postexpansion electoral system did not sufficiently dispel the adverse impact of the expansions on the relative political strength of the black community in Port Arthur. The city submits that this judgment was in error under Petersburg and Richmond.
  Richmond, however, involved a fairly drawn, single-member district system that adequately reflected the political strength of the black community in the enlarged city. The plan was consequently an acceptable response to the annexation’s adverse impact on minority voting potential. It does not necessarily follow that the mixed single-member and at-large system at issue in this case sufficiently dispelled the impact of Port Arthur’s expansions on the relative political strength of the black community. The District Court concluded that although the 4-2-3 system provided a black majority in three councilmanic districts, it was necessary also to eliminate the majority-vote requirement with respect to the two nonmayoral at-large council positions. For several reasons, we cannot say that the District Court erred in this respect.
  First, whether the 4-2-3 plan adequately reflected the political strength of the black minority in the enlarged city is not an issue that is determinable with mathematical precision. Because reasonable minds could differ on the question and because the District Court was sitting as a court of equity seeking to devise a remedy for what otherwise might be a statutory violation, we should not rush to overturn its judgment. Cf. Swann v. Charlotte-Mecklenburg Board of Education, 402 U. S. 1, 15 (1971).
  Second, the 4-2-3 plan undervalued to some extent the political strength of the black community: one-third of the Council seats was to be elected from black majority districts, but blacks constituted 40.56% of the population of the enlarged city and 35% of the voting age population. In light of this fact, eliminating the majority-vote requirement was an understandable adjustment. As the District Court well understood, the majority-vote rule, which forbade election by a plurality, would always require the black candidate in an at-large election, if he survived the initial round, to run against one white candidate. In the context of racial bloc voting prevalent in Port Arthur, the rule would permanently foreclose a black candidate from being elected to an at-large seat. Removal of the requirement, on the other hand, might enhance the chances of blacks to be elected to the two at-large seats affected by the District Court’s conditional order but surely would not guarantee that result. Only if there were two or more white candidates running in a district would a black have any chance of winning election under a plurality system. We cannot say that insisting on eliminating the majority-vote rule in the two at-large districts would either overvalue black voting strength in Port Arthur or be inconsistent with Richmond.
  Third, even if the 4-2-3 electoral scheme might otherwise be said to reflect the political strength of the minority community, the plan would nevertheless be invalid if adopted for racially discriminatory purposes, i.e., if the majority-vote requirement in the two at-large districts had been imposed for the purpose of excluding blacks from any realistic opportunity to represent those districts or to exercise any influence on Council members elected to those positions. City of Richmond v. United States, 422 U. S., at 378-379. The District Court made no finding that the 4-2-3 plan was tainted by an impermissible purpose; but it had found that the two preceding plans, the first nine-member plan and the 4r-4r-1 plan, had been adopted for the illicit purpose of preventing black candidates from winning election. The court had also found that the majority-vote requirement was a major means of effectuating this discriminatory end. When it was then presented with the 4-2-3 plan retaining the requirement for the two nonmayoral at-large seats, the Court conditioned approval on eliminating the majority-vote element. It seems to us that in light of the prior findings of discriminatory purpose such action was a reasonable hedge against the possibility that the 4-2-3 scheme contained a purposefully discriminatory element. On balance, we cannot fault the judgment of the District Court.
  The judgment of the District Court is accordingly
  Affirmed.
  It is undisputed that the city of Port Arthur is a political subdivision to which § 5 is applicable. See 28 CFR, p. 461, Appendix (1982).
  Section 5, as set forth in 42 U. S. C. § 1973c, in relevant part provides as follows:
  “Whenever a State or political subdivision with respect to which the prohibitions set forth in section 1973b(a) of this title based upon determinations made under the first sentence of section 1973b(b) of this title are in effect shall enact or seek to administer any voting qualification or prerequisite to voting, or standard, practice, or procedure with respect to voting different from that in force or effect. . . such State or subdivision may institute an action in the United States District Court for the District of Columbia for a declaratory judgment that such qualification, prerequisite, standard, practice, or procedure does not have the purpose and will not have the effect of denying or abridging the right to vote on account of race or color, or in contravention of the guarantees set forth in section 1973b(f)(2) of this title, and unless and until the court enters such judgment no person shall be denied the right to vote for failure to comply with such qualification, prerequisite, standard, practice, or procedure: Provided, That such qualification, prerequisite, standard, practice, or procedure may be enforced without such proceeding if the qualification, prerequisite, standard, practice, or procedure has been submitted by the chief legal officer or other appropriate official of such State or subdivision to the Attorney General and the Attorney General has not interposed an objection within sixty days after such submission, or upon good cause shown, to facilitate tate an expedited approval within sixty days after such submission, the Attorney General has affirmatively indicated that such objection will not be made.”
  The preannexation and postannexation percentages are based on the 1980 census. The figure for the percentage of blacks in the voting age population is an estimate, which the District Court derived by extrapolating from the 1970 census data. The 1970 census showed that at that time 34.6% of the voting age population was black while 40.01% of the general population was black. The District Court itself noted the dangers of extrapolation, but explained that both parties had suggested the procedure for determining the percentage of the current voting age population that is black. Port Arthur also has a Hispanic community, which comprises 6.30% of the enlarged city’s population.
  The United States unsuccessfully sought to enjoin the referendum election before a three-judge court in the Eastern District of Texas. United States v. City of Port Arthur, No. B-80-216-CA (Sept. 5, 1980).
  The city argues that the District Court was required to approve a plan jointly submitted by the city and the Attorney General. The Voting Rights Act, however, assigns primary responsibility to the District Court to determine whether a change in voting procedures violates § 5. Pre-clearance by the Attorney General may obviate a court suit, but here the Attorney General was acting in the capacity of a litigant when he joined the city in submitting a plan for the court’s consideration. In that posture, neither the Attorney General, the city, nor both of them together could dictate the court’s conclusion as to the acceptability of the plan under § 5.
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