Named black citizens of Albany, Georgia, joined by the United States, brought this class action to invalidate a 1947 law providing for at-large election of seven city officials. 1947 Ga.Laws p. 725. After finding that the at-large scheme had the inevitable effect of abridging the rights of black voters, the district court devised a plan calling for the election of five city commissioners ■from single member districts but preserving two positions (mayor and mayor pro tem.) to be chosen at-large. Paige v. Gray, 399 F.Supp. 459 (M.D.Ga.1975). Both sides (except for the United States) appeal. We vacate and remand for re-examination of the basis for the invalidation of the 1947 law and to provide the district court with an opportunity to reassess its adoption of a mixed single member and at-large plan in light of recent Supreme Court pronouncements.
The challenged at-large procedure was enacted by the Georgia Legislature in 1947 close on the heels of this court’s eradication of all-white primaries. Chapman v. King, 154 F.2d 460 (5th Cir.), cert. denied, 327 U.S. 800, 66 S.Ct. 905, 90 L.Ed. 1025 (1946). Prior to 1947, five city commissioners had been elected on a ward basis. 1923 Ga. Laws p. 374. Since 1923, however, two commissioners had been elected at large, and since 1937, these posts have been specifically designated as mayor and mayor pro tem. 1937 Ga.Laws p. 1476.
The end of discriminatory primaries enabled black voters to participate meaningfully in the 1946 ward elections for the first time. The black-preferred candidate (a white) won in Ward 5 where blacks constituted a majority of registered voters. This new-found political strength was quickly eroded by the 1947 legislation which had the effect of transforming a black ward majority into an at-large minority. The legislators were apparently so worried about black voter control that specific provisions were enacted in the 1947 law to guard against filling vacancies in Ward 5. 1947 Ga.Laws p. 734. To compound the problem for blacks a majority vote requirement was instituted in 1959. 1959 Ga.Laws p. 2950. No black has ever been elected under the at-large plan although the population is approximately 40% black. Only seven blacks have run for office; four of these ran in primaries of the Democratic Party.
The district court’s invalidation of the at-large scheme relied heavily upon Gomillion v. Lightfoot, 364 U.S. 339, 81 S.Ct. 125, 5 L.Ed.2d 110 (1960), the leading case prohibiting racial gerrymandering. Although expressly declining to rule on racial motivation or intent in the passage of the 1947 law, the court concluded that the harmful effect of the . legislation caused a violation of the Fifteenth Amendment. 399 F.Supp. at 463-64. The analysis of the constitution*1110ality of the voting statutes was halted at this point. The court refused to apply more recent Fourteenth Amendment precedents dealing with dilution of the black vote in multimember districts, stating that these cases should not be applied “retroactively” to election systems of long standing. Id. at 465-66.
The city and the private plaintiffs complain of the lower court’s action. The city contests the ruling on the merits, specifically questioning the applicability of Gomfflion to the facts of this case. The private plaintiffs cross-appeal solely on the issue of relief and urge adoption of a single-district plan for all seven city officials. The United States seeks an across-the-board affirmance of the district court’s decision.
I. Validity of the 1947 Act
Gomfflion involved an attempt by the City of Tuskegee to redraw its municipal boundaries to exclude virtually all black voters. The Gomfflion holding has most often been cited as a prohibition against racial gerrymandering or plans drawn along racial lines. See Wright v. Rockefeller, 376 U.S. 52, 84 S.Ct. 603, 11 L.Ed.2d 512 (1964); Howard v. Adams County Board of Supervisors, 453 F.2d 455, 457 (5th Cir. 1973); Sims v. Baggett, 247 F.Supp. 96, 105 (M.D. Ala. 1965) (three-judge court). Since the advent of the dilution decisions there has apparently been no need to resort to Gomfflion to eliminate unconstitutional at-large plans.1 Moreover, Gomfflion and its progeny have recently been interpreted to require proof of racial motivation or a showing that the election scheme was “conceived or operated as purposeful devices to further racial or economic discrimination.” Whitcomb v. Chavis, 403 U.S. 124, 149, 91 S.Ct. 1858, 1872, 29 L.Ed.2d 363 (1971).2
Notwithstanding Gomillion’s “inevitable effect” language, it is likely that the Supreme Court will require circumstantial proof of unlawful motive. See Washington v. Davis, - U.S. -, 96 S.Ct. 2040, 48 L.Ed.2d 597 (1976).3 Thus absent an express finding of discriminatory purpose, the application of Gomfflion to the assessment of an at-large election plan’s validity may be incomplete. ' Since we conclude that any evaluation of the 1947 law should be made under more recent and less ambiguous precedents, we do not reach the question of whether the sequence of events leading to the passage of the 1947 Act was sufficiently suspect to compel a finding of racial motivation.
The validity of Albany’s change from a ward to an at-large system can best be handled by applying the multifactor test enunciated in the recent dilution decisions of the Supreme Court and this circuit, notably White v. Regester, 412 U.S. 755, 93 S.Ct. 2332, 37 L.Ed.2d 314 (1973) and Zimmer v. McKeithen, 485 F.2d 1297 (5th Cir. 1973) (en banc).4
*1111The district court’s concern with the retroactive application of White and its progeny in this circuit is unwarranted. Prospectivity in the context of an election law challenge relates to the current and continuing use of the challenged enactment; it does not look to the date of enactment alone. The doctrine means no more than that the results of past elections will not be supplanted by special elections.5 It does not constitute a bar against issuing injunctions as to future elections. See Allen v. State Board of Elections, 393 U.S. 544, 571-72, 89 S.Ct. 817, 835, 22 L.Ed.2d 1 (1969). More importantly, the Supreme Court has never indicated that its dilution principles should only be used to test recently enacted provisions. To the contrary, White struck down a multimember scheme which had been in operation since at least 1914, although the specific charter provisions at issue were of more recent vintage.
The dilution decisions recognize that where multimember or at-large schemes are employed, collective strength of black voters may be diluted and the chances of electing representatives who are responsive to minority interests correspondingly lessened. To establish that a plan impermissibly dilutes, the plaintiff must show more than a mere disparity between percentage of minority residents and percentage of minority representation. The proof must affirmatively demonstrate that the affected group has less opportunity to participate in the political process. Zimmer sets the basic standard in this circuit:
Where a minority can demonstrate lack of access to the process of slating candidates, the unresponsiveness of legislators to their particularized interests, a tenuous state policy underlying the preference for multi-member or at-large districting, or that the existence of past discrimination in general precludes the effective participation in the election system, a strong case is made. Such proof is enhanced by a showing of the existence of large districts, majority vote requirements, anti-single shot voting provisions and the lack of provision for at-large candidates running from particular geographical subdistricts. The fact of dilution is established upon proof of the existence of an aggregate of these factors. The Supreme Court’s recent pronouncement in White v. Regester, supra, demonstrates, however, that all these factors need not be proved in order to obtain relief.
485 F.2d at 1305.
Both the private plaintiffs and the United States seek to justify the district court’s decision on the merits by applying the Zimmer factors. The weighing of these factors is ordinarily a trial court function which we will not undertake initially unless the record is so clear as to permit of only one resolution. We do not have to make this latter determination since the case must go back to the district court on the question of the propriety of providing for at-large elections as part of its remedial plan. Therefore, a remand for this inquiry also will not entail any significant increase in the chances for delay.
II. Relief •
The United States Supreme Court has very recently emphasized the rule that “when district courts are forced to fashion apportionment plans, single-member districts are preferable to larger multi-member districts as a general matter.” Connor v. Johnson, 402 U.S. 690, 692, 91 S.Ct. 1760, 1762, 29 L.Ed.2d 268 (1971). Absent a finding of special circumstances or insurmountable difficulties, the court should shape its remedial plan using single-member districts only. Wallace v. House, - U.S. -, 96 S.Ct. 1721, 48 L.Ed.2d 191 (1976), vacating, 515 F.2d 619 (5th Cir. 1975); East Carroll *1112Parish School Board v. Marshall, 424 U.S. 636, 96 S.Ct. 1083, 1085-86, 47 L.Ed.2d 296, 299 (1976). At oral argument in this court there was much debate concerning the role of Albany’s mayor and mayor pro tem. directed toward ascertaining whether these positions are so unusual or unique as to require a vote by the whole community. From that discussion we have concluded that this issue must be explored in depth by the court on remand. See Nevett v. Sides, 533 F.2d 1361, 1365-66 n.5 (5th Cir. 1976). The district court is at liberty to reopen the proof if it determines that further evidence may illuminate any issue to be decided by it. That court ultimately must apply the Supreme Court standard expressed in Con-nor, East Carroll, and Wallace to that completed record to determine whether any at-large elections at all should be allowed.6
VACATED AND REMANDED.
. Prior to the dilution precedents, Gomfflion was relied upon to invalidate a change from beat to at-large election of Democratic party officials in Barbour County, Alabama. Smith v. Paris, 257 F.Supp. 901 (M.D.Ala.1966), aff’d, 386 F.2d 979 (5th Cir. 1967). Likewise, Gomiilion has been used less frequently in gerrymander cases since the courts have not hesitated to apply recent dilution cases to solve redistricting problems. Gilbert v. Sterrett, 509 F.2d 1389 (5th Cir. 1975); Robinson v. Commissioners Court, 505 F'.2d 674 (5th Cir. 1974).
. The court in Smith v. Paris, 257 F.Supp. 901 (M.D.Ala. 1966) made an express finding of racial motivation before invalidating an at-large scheme on the basis of Gomfflion.
. The majority in Davis cited Wright v. Rockefeller, 376 U.S. 52, 84 S.Ct. 603, 11 L.Ed.2d 512 (1964), the direct descendant of Gomfflion, for the proposition that proof of a racial purpose is necessary to establish a Fourteenth Amendment violation. In his concurring opinion, Mr. Justice Stevens agreed with the majority’s statement of a general rule requiring proof of discriminatory intent but noted that in cases such as Gomfflion where the disproportionate impact is so dramatic, “it really does not matter whether the standard is phrased in terms of purpose or effect.” -U.S. at-, 96 S.Ct. at 2054.
. This court’s decision in Zimmer was affirmed by the Supreme Court, “but without approval of the constitutional views expressed by the Court of Appeals.” East Carroll Parish School Board v. Marshall, 424 U.S. 636, 638, 96 S.Ct. 1083, 1085, 47 L.Ed.2d 296, 299 (1976). The Zimmer standards, however, are still controlling in this circuit. McGill v. Gadsden *1111County Commission, 535 F.2d 277 (5th Cir. 1976); Nevett v. Sides, 533 F.2d 1361 (5th Cir. 1976).
. As the district court recognized, officials elected under a law subsequently declared invalid remain de facto in office until new elections can be held and successors chosen. Likewise, the city officials elected in 1975 under the court plan will continue in office as directed unless and until a new plan is ordered.
. In light of Judge Ainsworth’s special concurrence, the majority deems it appropriate to expressly disavow any intention of adding to or detracting from the precedents referred to above. The decision as to whether their application to the facts presented by this case should produce a single member district or an at-large election requirement for any of the officers involved is committed to the district court in the first instance. That court should not assume that this opinion has the slightest intent to tilt its judgment in either direction.