[837] Justice Powell
delivered the opinion of the Court.
The issue is whether the State of Wyoming violated the Equal Protection Clause by allocating one of the 64 seats in its House of Representatives to a county the population of which is considerably lower than the average population per state representative.
I
Since Wyoming became a State in 1890, its legislature has consisted of a Senate and a House of Representatives. The State’s Constitution provides that each of the State’s counties “shall constitute a senatorial and representative district” and that “[e]ach county shall have at least one senator and one representative.” The senators and representatives are required to be “apportioned among the said counties as nearly as may be according to the number of their inhabitants.” Wyo. Const., Art. 3, §3.1 The State has had 23 counties since 1922. Because the apportionment of the Wyoming House has been challenged three times in the past 20 years, some background is helpful.
In 1963 voters from the six most populous counties filed suit in the District Court for the District of Wyoming challenging the apportionment of the State’s 25 senators and 61 representatives. The three-judge District Court held that the apportionment of the Senate — one senator allocated to each of the State’s 23 counties, with the two largest counties having two senators — so far departed from the principle of population equality that it was unconstitutional. Schaefer v. Thomson, 240 F. Supp. 247, 251-252 (Wyo. 1964), supple[838] mented, 251 F. Supp. 450 (1965), aff’d sub nom. Harrison v. Schaefer, 383 U. S. 269 (1966).2 But the court upheid the apportionment of the State House of Representatives. The State’s constitutional requirement that each county shall have at least one representative had produced deviations from population equality: the average deviation from the ideal number of residents per representative was 16%, while the maximum percentage deviation between largest and smallest number of residents per representative was 90%. See 1 App. Exhibits 16. The District Court held that these population disparities were justifiable as “the result of an honest attempt, based on legitimate considerations, to effectuate a rational and practical policy for the house of representatives under conditions as they exist in Wyoming.” 240 F. Supp., at 251.
The 1971 reapportionment of the House was similar to that in 1963, with an average deviation of 15% and a maximum deviation of 86%. 1 App. Exhibits 18. Another constitutional challenge was brought in the District Court. The three-judge court again upheld the apportionment of the House, observing that only “five minimal adjustments” had been made since 1963, with three districts gaining a representative and two districts losing a representative because of population shifts. Thompson v. Thomson, 344 F. Supp. 1378, 1380 (Wyo. 1972).
The present case is a challenge to Wyoming’s 1981 statute reapportioning its House of Representatives in accordance with the requirements of Art. 3, § 3, of the State Constitution. Wyo. Stat. §28-2-109 (Supp. 1983).3 The 1980 census [839] placed Wyoming’s population at 469,557. The statute provided for 64 representatives, meaning that the ideal apportionment would be 7,337 persons per representative. Each county was given one representative, including the six counties the population of which fell below 7,337. The deviations from population equality were similar to those in prior decades, with an average deviation of 16% and a maximum deviation of 89%. See 1 App. Exhibits 19-20.
The issue in this case concerns only Niobrara County, the State’s least populous county. Its population of 2,924 is less than half of the ideal district of 7,337. Accordingly, the general statutory formula would have dictated that its population for purposes of representation be rounded down to zero. See § 28 — 2—109(a)(ii). This would have deprived Niobrara County of its own representative for the first time since it became a county in 1913. The state legislature found, however, that “the opportunity for oppression of the people of this state or any of them is greater if any county is deprived a representative in the legislature than if each is guaranteed at least one (1) representative.”4 It therefore followed the [840] State Constitution’s requirement and expressly provided that a county would receive a representative even if the statutory formula rounded the county’s population to zero. § 28 — 2—109(a)(iii). Niobrara County thus was given one seat in a 64-seat House. The legislature also provided that if this representation for Niobrara County were held unconstitutional, it would be combined with a neighboring county in a single representative district. The House then would consist of 63 representatives. § 28-2-109(a)(iv).
Appellants, members of the state League of Women Voters and residents of seven counties in which the population per representative is greater than the state average, filed this lawsuit in the District Court for the District of Wyoming. They alleged that “[b]y granting Niobrara County a representative to which it is not statutorily entitled, the voting privileges of Plaintiffs and other citizens and electors of Wyoming similarly situated have been improperly and illegally diluted in violation of the 14th Amendment. . . .” App. 3-4. They sought declaratory and injunctive relief that would prevent the State from giving a separate representative to Nio-[841] brara County, thus implementing the alternative plan calling for 63 representatives.
The three-judge District Court upheld the constitutionality of the statute. 536 F. Supp. 780 (1982). The court noted that the narrow issue presented was the alleged discriminatory effect of a single county’s representative, and concluded, citing expert testimony, that “the ‘dilution’ of the plaintiffs’ votes is de minimis when Niobrara County has its own representative.” Id., at 783. The court also found that Wyoming’s policy of granting a representative to each county was rational and, indeed, particularly well suited to the special needs of Wyoming. Id., at 784.5
We noted probable jurisdiction, 459 U. S. 819 (1982), and now affirm.
[842] HH H-1
A
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[837] Justice Powell
delivered the opinion of the Court.
The issue is whether the State of Wyoming violated the Equal Protection Clause by allocating one of the 64 seats in its House of Representatives to a county the population of which is considerably lower than the average population per state representative.
I
Since Wyoming became a State in 1890, its legislature has consisted of a Senate and a House of Representatives. The State’s Constitution provides that each of the State’s counties “shall constitute a senatorial and representative district” and that “[e]ach county shall have at least one senator and one representative.” The senators and representatives are required to be “apportioned among the said counties as nearly as may be according to the number of their inhabitants.” Wyo. Const., Art. 3, §3.1 The State has had 23 counties since 1922. Because the apportionment of the Wyoming House has been challenged three times in the past 20 years, some background is helpful.
In 1963 voters from the six most populous counties filed suit in the District Court for the District of Wyoming challenging the apportionment of the State’s 25 senators and 61 representatives. The three-judge District Court held that the apportionment of the Senate — one senator allocated to each of the State’s 23 counties, with the two largest counties having two senators — so far departed from the principle of population equality that it was unconstitutional. Schaefer v. Thomson, 240 F. Supp. 247, 251-252 (Wyo. 1964), supple[838] mented, 251 F. Supp. 450 (1965), aff’d sub nom. Harrison v. Schaefer, 383 U. S. 269 (1966).2 But the court upheid the apportionment of the State House of Representatives. The State’s constitutional requirement that each county shall have at least one representative had produced deviations from population equality: the average deviation from the ideal number of residents per representative was 16%, while the maximum percentage deviation between largest and smallest number of residents per representative was 90%. See 1 App. Exhibits 16. The District Court held that these population disparities were justifiable as “the result of an honest attempt, based on legitimate considerations, to effectuate a rational and practical policy for the house of representatives under conditions as they exist in Wyoming.” 240 F. Supp., at 251.
The 1971 reapportionment of the House was similar to that in 1963, with an average deviation of 15% and a maximum deviation of 86%. 1 App. Exhibits 18. Another constitutional challenge was brought in the District Court. The three-judge court again upheld the apportionment of the House, observing that only “five minimal adjustments” had been made since 1963, with three districts gaining a representative and two districts losing a representative because of population shifts. Thompson v. Thomson, 344 F. Supp. 1378, 1380 (Wyo. 1972).
The present case is a challenge to Wyoming’s 1981 statute reapportioning its House of Representatives in accordance with the requirements of Art. 3, § 3, of the State Constitution. Wyo. Stat. §28-2-109 (Supp. 1983).3 The 1980 census [839] placed Wyoming’s population at 469,557. The statute provided for 64 representatives, meaning that the ideal apportionment would be 7,337 persons per representative. Each county was given one representative, including the six counties the population of which fell below 7,337. The deviations from population equality were similar to those in prior decades, with an average deviation of 16% and a maximum deviation of 89%. See 1 App. Exhibits 19-20.
The issue in this case concerns only Niobrara County, the State’s least populous county. Its population of 2,924 is less than half of the ideal district of 7,337. Accordingly, the general statutory formula would have dictated that its population for purposes of representation be rounded down to zero. See § 28 — 2—109(a)(ii). This would have deprived Niobrara County of its own representative for the first time since it became a county in 1913. The state legislature found, however, that “the opportunity for oppression of the people of this state or any of them is greater if any county is deprived a representative in the legislature than if each is guaranteed at least one (1) representative.”4 It therefore followed the [840] State Constitution’s requirement and expressly provided that a county would receive a representative even if the statutory formula rounded the county’s population to zero. § 28 — 2—109(a)(iii). Niobrara County thus was given one seat in a 64-seat House. The legislature also provided that if this representation for Niobrara County were held unconstitutional, it would be combined with a neighboring county in a single representative district. The House then would consist of 63 representatives. § 28-2-109(a)(iv).
Appellants, members of the state League of Women Voters and residents of seven counties in which the population per representative is greater than the state average, filed this lawsuit in the District Court for the District of Wyoming. They alleged that “[b]y granting Niobrara County a representative to which it is not statutorily entitled, the voting privileges of Plaintiffs and other citizens and electors of Wyoming similarly situated have been improperly and illegally diluted in violation of the 14th Amendment. . . .” App. 3-4. They sought declaratory and injunctive relief that would prevent the State from giving a separate representative to Nio-[841] brara County, thus implementing the alternative plan calling for 63 representatives.
The three-judge District Court upheld the constitutionality of the statute. 536 F. Supp. 780 (1982). The court noted that the narrow issue presented was the alleged discriminatory effect of a single county’s representative, and concluded, citing expert testimony, that “the ‘dilution’ of the plaintiffs’ votes is de minimis when Niobrara County has its own representative.” Id., at 783. The court also found that Wyoming’s policy of granting a representative to each county was rational and, indeed, particularly well suited to the special needs of Wyoming. Id., at 784.5
We noted probable jurisdiction, 459 U. S. 819 (1982), and now affirm.
[842] HH H-1
A
In Reynolds v. Sims, 377 U. S. 533, 568 (1964), the Court held that “the Equal Protection Clause requires that the seats in both houses of a bicameral state legislature must be apportioned on a population basis.” This holding requires only “that a State make an honest and good faith effort to construct districts ... as nearly of equal population as is practicable,” for “it is a practical impossibility to arrange legislative districts so that each one has an identical number of residents, or citizens, or voters.” Id., at 577. See Gaffney v. Cummings, 412 U. S. 735, 745-748 (1973) (describing various difficulties in measurement of population).
We have recognized that some deviations from population equality may be necessary to permit the States to pursue other legitimate objectives such as “maintain[ing] the integrity of various political subdivisions” and “providing] for compact districts of contiguous territory.” Reynolds, supra, at 578. As the Court stated in Gaffney, “[a]n unrealistic overemphasis on raw population figures, a mere nose count in the districts, may submerge these other considerations and itself furnish a ready tool for ignoring factors that in day-to-day operation are important to an acceptable representation and apportionment arrangement.” 412 U. S., at 749.
In view of these considerations, we have held that “minor deviations from mathematical equality among state legislative districts are insufficient to make out a prima facie case of invidious discrimination under the Fourteenth Amendment so as to require justification by the State.” Id., at 745. Our decisions have established, as a general matter, that an apportionment plan with a maximum population deviation under 10% falls within this category of minor deviations. See, e. g., Connor v. Finch, 431 U. S. 407, 418 (1977); White v. Regester, 412 U. S. 755, 764 (1973). A plan with larger [843] disparities in population, however, creates a prima facie case of discrimination and therefore must be justified by the State. See Swann v. Adams, 385 U. S. 440, 444 (1967) (“De minimis deviations are unavoidable, but variations of 30% among senate districts and 40% among house districts can hardly be deemed de minimis and none of our cases suggests that differences of this magnitude will be approved without a satisfactory explanation grounded on acceptable state policy”). The ultimate inquiry, therefore, is whether the legislature’s plan “may reasonably be said to advance [a] rational state policy” and, if so, “whether the population disparities among the districts that have resulted from the pursuit of this plan exceed constitutional limits.” Mahan v. Howell, 410 U. S. 315, 328 (1973).
B
In this case there is no question that Niobrara County’s deviation from population equality — 60% below the mean — is more than minor. There also can be no question that Wyoming’s constitutional policy — followed since statehood — of using counties as representative districts and ensuring that each county has one representative is supported by substantial and legitimate state concerns. In Abate v. Mundt, 403 U. S. 182, 185 (1971), the Court held that “a desire to preserve the integrity of political subdivisions may justify an apportionment plan which departs from numerical equality.” See Mahan v. Howell, supra, at 329. Indeed, the Court in Reynolds v. Sims, supra, singled out preservation of political subdivisions as a clearly legitimate policy. See 377 U. S., at 580-581.
Moreover, it is undisputed that Wyoming has applied this factor in a manner “free from any taint of arbitrariness or discrimination.” Roman v. Sincock, 377 U. S. 695, 710 (1964). The State’s policy of preserving county boundaries is based on the State Constitution, has been followed for decades, and has been applied consistently throughout the State. As the [844] District Court found, this policy has particular force, given the peculiar size and population of the State and the nature of its governmental structure. See n. 5, supra; 536 F. Supp., at 784. In addition, population equality is the sole other criterion used, and the State’s apportionment formula ensures that population deviations are no greater than necessary to preserve counties as representative districts. See Mahan v. Howell, supra, at 326 (evidence is clear that the plan “ ‘produces the minimum deviation above and below the norm, keeping intact political boundaries’ ”). Finally, there is no evidence of “a built-in bias tending to favor particular political interests or geographic areas.” Abate v. Mundt, supra, at 187. As Judge Doyle stated below:
“[T]here is not the slightest sign of any group of people being discriminated against here. There is no indication that the larger cities or towns are being discriminated against; on the contrary, Cheyenne, Laramie, Casper, Sheridan, are not shown to have suffered in the slightest . . . degree. There has been no preference for the cattle-raising or agricultural areas as such.” 536 F. Supp., at 788 (specially concurring).
In short, this case presents an unusually strong example of an apportionment plan the population variations of which are entirely the result of the consistent and nondiscriminatory application of a legitimate state policy.6 This does not mean [845] that population deviations of any magnitude necessarily are acceptable. Even a neutral and consistently applied criterion such as use of counties as representative districts can frustrate Reynolds’ mandate of fair and effective representation if the population disparities are excessively high.7 “[A] State’s policy urged in justification of disparity in district population, however rational, cannot constitutionally be permitted to emasculate the goal of substantial equality.” Mahan v. Howell, supra, at 326. It remains true, however, as the Court in Reynolds noted, that consideration must be given “to the character as well as the degree of deviations from a strict population basis.” 377 U. S., at 581. The consistency of application and the neutrality of effect of the [846] nonpopulation criteria must be considered along with the size of the population disparities in determining whether a state legislative apportionment plan contravenes the Equal Protection Clause.
C
Here we are not required to decide whether Wyoming’s nondiscriminatory adherence to county boundaries justifies the population deviations that exist throughout Wyoming’s representative districts. Appellants deliberately have limited their challenge to the alleged dilution of their voting power resulting from the one representative given to Nio-brara County.8 The issue therefore is not whether a 16% average deviation and an 89% maximum deviation, considering the state apportionment plan as a whole, are constitutionally permissible. Rather, the issue is whether Wyoming’s policy of preserving county boundaries justifies the additional deviations from population equality resulting from the provision of representation to Niobrara County.9
[847] It scarcely can be denied that in terms of actual effect on appellants’ voting power, it matters little whether the 63-member or 64-member House is used. The District Court noted, for example, that the seven counties in which appellants reside will elect 28 representatives under either plan. The only difference, therefore, is whether they elect 43.75% of the legislature (28 of 64 members) or 44.44% of the legislature (28 of 63 members). 536 F. Supp., at 783.10 The District Court aptly described this difference as “de minimis.” Ibid.
We do not suggest that a State is free to create and allocate an additional representative seat in any way it chooses simply because that additional seat will have little or no effect on the remainder of the State’s voters. The allocation of a representative to a particular political subdivision still may violate the Equal Protection Clause if it greatly exceeds the population variations existing in the rest of the State and if the State provides no legitimate justifications for the creation of that seat. Here, however, considerable population variations will remain even if Niobrara County’s representative is eliminated. Under the 63-member plan, the average deviation per representative would be 13% and the maximum deviation would be 66%. See 1 App. Exhibits 22. These statistics make clear that the grant of a representative to Niobrara County is not a significant cause of the population deviations that exist in Wyoming.
Moreover, we believe that the differences between the two plans are justified on the basis of Wyoming’s longstanding and legitimate policy of preserving county boundaries. See swpra, at 841, n. 5, and 843-844. Particularly where there is no “taint of arbitrariness or discrimination,” Roman v. Sincock, 377 U. S., at 710, substantial deference is to be accorded the political decisions of the people of a State acting [848] through their elected representatives. Here it is noteworthy that by enacting the 64-member plan the State ensured that its policy of preserving county boundaries applies nondiscriminatorily. The effect of the 63-member plan would be to deprive the voters of Niobrara County of their own representative, even though the remainder of the House of Representatives would be constituted so as to facilitate representation of the interests of each county. See 536 F. Supp., at 784; id., at 786 (Doyle, J., specially concurring). In these circumstances, we are not persuaded that Wyoming has violated the Fourteenth Amendment by permitting Nio-brara County to have its own representative.
The judgment of the District Court is
Affirmed.