Opinion

JUSTICE O'CONNOR delivered the opinion of the Court.

Appellants urge us to hold that the Equal Protection Clause forbids a State to allow some local school boards, but not others, to assess a fee for transporting pupils between their homes and the public schools. Applying well-established equal protection principles, we reject this claim and affirm the constitutionality of the challenged statute.

I

North Dakota is a sparsely populated State, with many people living on isolated farms and ranches. One result has been that some children, as late as the mid-20th century, were educated in

the one-room school where, in many cases, there [we]re twenty or more pupils with one teacher attempting in crowded conditions and under other disadvantages to give instructions in all primary grades.

Herman v. Medicine Lodge School Dist. No. 8, 71 N.W.2d 323, 328 (N.D.1955). The State has experimented with various ameliorative devices at different times in its history. Beginning in 1907, for example, it has adopted a series of policies that,

in certain circumstances required, and in other circumstances merely authorized, [local public] school districts to participate in transporting or providing compensation for transporting students to school.

402 N.W.2d 897, 900 (N.D.1987) (opinion below).

Since 1947, the legislature has authorized and encouraged thinly populated school districts to consolidate or "reorganize" themselves into larger districts so that education can be provided more efficiently. See Herman, supra, at 328; N.D.Cent.Code, ch. 15-27.3 (Supp.1987). Reorganization proposals, which obviously must contemplate an increase in the distance that some children travel to school, are required by law to include provisions for transporting students back and forth from their homes. See § 15-27.3-10. The details of these provisions may vary from district to district, but once a reorganization plan is adopted, the transportation provisions can be changed only with the approval of the voters. See §§ 15-27.3-10 and 15-27.3-19.

Appellee Dickinson Public Schools, which serves a relatively populous area, has chosen not to participate in such a reorganization. Until 1973, this school system provided free bus service to students in outlying areas, but the "pickup points" for this service were often at considerable distances from the students' homes. After a plebiscite of the bus users, Dickinson's School Board instituted door-to-door bus service and began charging a fee. During the period relevant to this case, about 13% of the students rode the bus; their parents were charged $97 per year for one child or $150 per year for two children. 402 N.W.2d at 898. Such fees covered approximately 11% of the cost of providing the bus service, and the remainder was provided from state and local tax revenues. Ibid.

In 1979, the State enacted the legislation at issue in this case. This statute expressly indicates that nonreorganized school districts, like Dickinson, may charge a fee for transporting students to school; such fees, however, may not exceed the estimated cost to the school district of providing the service. See N.D.Cent.Code § 15-34.2-06.1 (1981 and Supp.1987). The current version of this provision, which for convenience will be referred to as the "1979 statute," states in full:

Charge for bus transportation optional. The school board of any school district which has not been reorganized may charge a fee for schoolbus service provided to anyone riding on buses provided by the school district. For schoolbus service which was started prior to July 1, 1981, the total fees collected may not exceed an amount equal to the difference between the state transportation payment and the state average cost for transportation or the local school district's cost, whichever is the lesser amount. For schoolbus service started on or after July 1, 1981, the total fees collected may not exceed an amount equal to the difference between the state transportation payment and the local school district's cost for transportation during the preceding school year. Any districts that have not previously provided transportation for pupils may establish charges based on costs estimated by the school board during the first year that transportation is provided.

Appellants are a Dickinson schoolchild, Sarita Kadrmas, and her mother, Paula. The Kadrmas family, which also includes Mrs. Kadrmas' husband and two preschool children, lives about 16 miles from Sarita's school. Mr. Kadrmas works sporadically in the North Dakota oil fields, and the family's annual income at the time of trial was at or near the officially defined poverty level. Until 1985, the Kadrmas family had agreed each year to pay the fee for busing Sarita to school. Having fallen behind on these and other bills, however, the family refused to sign a contract obligating them to pay $97 for the 1985 school year. Accordingly, the school bus no longer stopped for Sarita, and the family arranged to transport her to school privately. The costs they incurred that year for Sarita's transportation exceeded $1,000, or about 10 times the fee charged by the school district for bus service. This arrangement continued until the spring of 1987, when Paula Kadrmas signed a bus service contract for the remainder of the 1986 school year and paid part of the fee. Mrs. Kadrmas later signed another contract for the 1987 school year, and paid about half of the fee for that period.

In September, 1985, appellants, along with others who have since withdrawn from the case, filed an action in state court seeking to enjoin appellees -the Dickinson Public Schools and various school district officials -from collecting any fee for the bus service. The action was dismissed on the merits, and an appeal was taken to the Supreme Court of North Dakota. After rejecting a state law challenge, which is not at issue here, the court considered appellants' claim that the busing fee violates the Equal Protection Clause of the Fourteenth Amendment. The court characterized the 1979 statute as "purely economic legislation," which "must be upheld unless it is patently arbitrary and fails to bear a rational relationship to any legitimate government purpose." 402 N.W.2d at 902. The court then concluded

that the charges authorized [by the statute] are rationally related to the legitimate governmental objective of allocating limited resources, and that the statute does not discriminate on the basis of wealth so as to violate federal or state equal protection rights.

Id. at 903. The court also rejected the contention that the distinction drawn by the statute between reorganized and nonreorganized school districts violates the Equal Protection Clause. The distinction, the court found, serves the legitimate objective of promoting reorganization "by alleviating parental concerns regarding the cost of student transportation in the reorganized district." Ibid. Three justices dissented on state law grounds. We noted probable jurisdiction, 484 U.S. 813 (1987), and now affirm.

II

A

Before addressing the merits, we must consider appellees' suggestion that this appeal should be dismissed on procedural grounds. After the decision of the Supreme Court of North Dakota in this case, Mrs. Kadrmas signed two bus service contracts and made partial payment on each. Since the execution of the first contract on April 6, 1987, Sarita has been riding the bus to school, or as appellees put it, "has been continuously enjoying the benefits of such bus service." Motion to Dismiss 1. Relying on Fahey v. Mallonee, 332 U. S. 245 (1947), appellees contend that appellants are "estopped" from pursuing their constitutional claims because "[i]t is well established that one may not retain benefits of an act while attacking the constitutionality of the same act." Motion to Dismiss 1-3.

Fahey was a shareholders' derivative suit in which a savings and loan association created under an Act of Congress sought to challenge the constitutionality of that same Act. This Court refused to consider the challenge, saying:

It would be difficult to imagine a more appropriate situation in which to apply the doctrine that one who utilizes an Act to gain advantages of corporate existence is estopped from questioning the validity of its vital conditions.

332 U.S. at 332 U. S. 256 (emphasis added). The case before us today is not analogous. Appellants obviously are not creatures of any statute, and we doubt that plaintiffs are generally forbidden to challenge a statute simply because they are deriving some benefit from it. Cf. United States v. San Francisco, 310 U. S. 16, 310 U. S. 28 -30 (1940); Arnett v. Kennedy, 416 U. S. 134, 416 U. S. 152 -153 (1974) (plurality opinion). The "benefit" derived by appellants from the challenged statute, moreover, is inapparent. The Dickinson School Board's authority to provide bus transportation is not given by the challenged statute, but by a different provision of state law. See N.D.Cent.Code § 15-34.2-01 (1981). Nor does the 1979 statute itself authorize the tax-supported subsidies that make the Dickinson school bus particularly attractive to parents in outlying areas. The fee that Dickinson is permitted to charge under the 1979 statute is itself a burden, rather than a benefit, to appellants, and they are not estopped from raising an equal protection challenge to the statute that imposes that burden on them.

Appellees also assert that execution of the bus service contracts rendered this case "moot." Brief for Appellees 32. Although appellees do not elaborate this contention or distinguish it from the estoppel argument just considered, they may be suggesting the absence of an Article III "case or controversy." If so, they are mistaken. Appellants claim that the 1979 statute is unconstitutional to the extent that it authorizes Dickinson to charge a fee for bus service, and they seek to prevent such fees from being collected. A decision in their favor might relieve them from paying the balance still owing under the two contracts that were executed in 1987, and would certainly relieve them from future assessments for bus service under the authority of the challenged statute. Because Sarita was only nine years old at the time of trial, and because there are two younger children in the family, the ongoing and concrete nature of the controversy between appellants and the Dickinson Public Schools is readily apparent.

B

Unless a statute provokes "strict judicial scrutiny" because it interferes with a "fundamental right" or discriminates against a "suspect class," it will ordinarily survive an equal protection attack so long as the challenged classification is rationally related to a legitimate governmental purpose. See, e.g., San Antonio Independent School Dist. v. Rodriguez, 411 U. S. 1, 411 U. S. 16 -17 (1973); Plyler v. Doe, 457 U. S. 202, 457 U. S. 216 -217 (1982); Lyng v. Automobile Workers, 485 U. S. 360, 485 U. S. 370 (1988). Appellants contend that Dickinson's user fee for bus service unconstitutionally deprives those who cannot afford to pay it of "minimum access to education." See Brief for Appellants i. Sarita Kadrmas, however, continued to attend school during the time that she was denied access to the school bus. Appellants must therefore mean to argue that the busing fee unconstitutionally places a greater obstacle to education in the path of the poor than it does in the path of wealthier families. Alternatively, appellants may mean to suggest that the Equal Protection Clause affirmatively requires government to provide free transportation to school, at least for some class of students that would include Sarita Kadrmas. Under either interpretation of appellants' position, we are evidently being urged to apply a form of strict or "heightened" scrutiny to the North Dakota statute. Doing so would require us to extend the requirements of the Equal Protection Clause beyond the limits recognized in our cases, a step we decline to take.

We have previously rejected the suggestion that statutes having different effects on the wealthy and the poor should on that account alone be subjected to strict equal protection scrutiny. See, e.g., Harris v. McRae, 448 U. S. 297, 448 U. S. 322 -323 (1980); Ortwein v. Schwab, 410 U. S. 656, 410 U. S. 660 (1973). Nor have we accepted the proposition that education is a "fundamental right," like equality of the franchise, which should trigger strict scrutiny when government interferes with an individual's access to it. See Papasan v. Allain, 478 U. S. 265, 478 U. S. 284 (1986); Plyler v. Doe, supra, at 457 U. S. 223 ; San Antonio Independent School Dist. v. Rodriguez, supra, at 411 U. S. 16, 411 U. S. 33 -36.

Relying primarily on Plyler v. Doe, supra, however, appellants suggest that North Dakota's 1979 statute should be subjected to "heightened" scrutiny. This standard of review, which is less demanding than "strict scrutiny" but more demanding than the standard rational relation test, has generally been applied only in cases that involved discriminatory classifications based on sex or illegitimacy. See, e.g., Clark v. Jeter, 486 U. S. 456, 486 U. S. 461 (1988); Mississippi University for Women v. Hogan, 458 U. S. 718, 458 U. S. 723 -724, and n. 9 (1982); Mills v. Habluetzel, 456 U. S. 91, 456 U. S. 101, and n. 8 (1982); Craig v. Boren, 429 U. S. 190, 429 U. S. 197 (1976). In Plyler, which did not fit this pattern, the State of Texas had denied to the children of illegal aliens the free public education that it made available to other residents. Applying a heightened level of equal protection scrutiny, the Court concluded that the State had failed to show that its classification advanced a substantial state interest. 457 U.S. at 457 U. S. 217 -218, and n. 16, 457 U. S. 224, 457 U. S. 230. We have not extended this holding beyond the "unique circumstances," id. at 457 U. S. 239 (Powell, J., concurring), that provoked its "unique confluence of theories and rationales," id. at 457 U. S. 243 (Burger, C.J., dissenting). Nor do we think that the case before us today is governed by the holding in Plyler. Unlike the children in that case, Sarita Kadrmas has not been penalized by the government for illegal conduct by her parents. See id. at 457 U. S. 220 ; id. at 457 U. S. 238 (Powell, J., concurring). On the contrary, Sarita was denied access to the school bus only because her parents would not agree to pay the same user fee charged to all other families that took advantage of the service. Nor do we see any reason to suppose that this user fee will

promot[e] the creation and perpetuation of a subclass of illiterates within our boundaries, surely adding to the problems and costs of unemployment, welfare, and crime.

Id. at 457 U. S. 230 ; see also id. at 457 U. S. 239 (Powell, J., concurring). Cf. N.D.Cent.Code § 15-43-11.2 (1981) ("A [school] board may waive any fee if any pupil or his parent or guardian shall be unable to pay such fees. No pupil's rights or privileges, including the receipt of grades or diplomas, may be denied or abridged for nonpayment of fees"). The case before us does not resemble Plyler, and we decline to extend the rationale of that decision to cover this case.

Appellants contend, finally, that whatever label is placed on the standard of review, this case is analogous to decisions in which we have held that government may not withhold certain especially important services from those who are unable to pay for them. Appellants cite Griffin v. Illinois, 351 U. S. 12 (1956) (right to appellate review of a criminal conviction conditioned on the purchase of a trial transcript); Smith v. Bennett, 365 U. S. 708 (1961) (application for writ of habeas corpus accepted only when accompanied by a filing fee); Boddie v. Connecticut, 401 U. S. 371 (1971) (action for dissolution of marriage could be pursued only upon payment of court fees and costs for service of process); Lindsey v. Normet, 405 U. S. 56 (1972) (appeal from civil judgments in certain landlord-tenant disputes conditioned on the posting of a bond for twice the amount of rent expected to accrue during the appellate process); and Little v. Streater, 452 U. S. 1 (1981) (fee for blood test in quasi-criminal paternity action brought against the putative father of a child receiving public assistance). See Brief for Appellants 22-23.

Leaving aside other distinctions that might be found between these cases and the one before us today, each involved a rule that barred indigent litigants from using the judicial process in circumstances where they had no alternative to that process. Decisions invalidating such rules are inapposite here. In contrast to the "utter exclusiveness of court access and court remedy," United States v. Kras, 409 U. S. 434, 409 U. S. 445 (1973), North Dakota does not maintain a legal or a practical monopoly on the means of transporting children to school. Thus, unlike the complaining parties in all the cases cited by appellants, the Kadrmas family could and did find a private alternative to the public school bus service for which Dickinson charged a fee. That alternative was more expensive, to be sure, and we have no reason to doubt that genuine hardships were endured by the Kadrmas family when Sarita was denied access to the bus. Such facts, however, do not imply that the Equal Protection Clause has been violated. In upholding a filing fee for voluntary bankruptcy actions, for example, we observed:

[B]ankruptcy is not the only method available to a debtor for the adjustment of his legal relationship with his creditors.... However unrealistic the remedy may be in a particular situation, a debtor, in theory, and often in actuality, may adjust his debts by negotiated agreement with his creditors.

Ibid. Similarly, we upheld a statute that required indigents to pay a filing fee for appellate review of adverse welfare benefits decisions. Ortwein v. Schwab, 410 U. S. 656 (1973). Noting that the case did not involve a "suspect classification," we held that the "applicable standard is that of rational justification." Id. at 410 U. S. 660. It is plain that the busing fee in this case more closely resembles the fees that were upheld in Kras and Ortwein than it resembles the fees that were invalidated in the cases on which appellants rely. Those cases therefore do not support the suggestion that North Dakota's 1979 statute violates the Equal Protection Clause. *

Applying the appropriate test -under which a statute is upheld if it bears a rational relation to a legitimate government objective -we think it is quite clear that a State's decision to allow local school boards the option of charging patrons a user fee for bus service is constitutionally permissible. The Constitution does not require that such service be provided at all, and it is difficult to imagine why choosing to offer the service should entail a constitutional obligation to offer it for free. No one denies that encouraging local school districts to provide school bus service is a legitimate state purpose, or that such encouragement would be undermined by a rule requiring that general revenues be used to subsidize an optional service that will benefit a minority of the district's families. It is manifestly rational for the State to refrain from undermining its legitimate objective with such a rule.

C

Appellants contend that, even without the application of strict or heightened scrutiny, the 1979 statute violates equal protection because it permits user fees for bus service only in nonreorganized school districts. This distinction, they say, can be given no rational justification whatsoever. Brief for Appellants 19-22. The principles governing our review of this claim are well established.

'The Fourteenth Amendment does not prohibit legislation merely because it is special, or limited in its application to a particular geographical or political subdivision of the state.' Fort Smith Light Co. v. Paving Dist., 274 U. S. 387, 274 U. S. 391 (1927). Rather, the Equal Protection Clause is offended only if the statute's classification 'rests on grounds wholly irrelevant to the achievement of the State's objective.' McGowan v. Maryland, 366 U. S. 420, 366 U. S. 425 (1961); Kotch v. Board of River Port Pilot Comm'rs, 330 U. S. 552, 330 U. S. 556 (1947).

Holt Civic Club v. Tuscaloosa, 439 U. S. 60, 439 U. S. 71 (1978). Social and economic legislation like the statute at issue in this case, moreover, "carries with it a presumption of rationality that can only be overcome by a clear showing of arbitrariness and irrationality." Hodel v. Indiana, 452 U. S. 314, 452 U. S. 331 -332 (1981).

[W]e will not overturn such a statute unless the varying treatment of different groups or persons is so unrelated to the achievement of any combination of legitimate purposes that we can only conclude that the legislature's actions were irrational.

Vance v. Bradley, 440 U. S. 93, 440 U. S. 97 (1979). In performing this analysis, we are not bound by explanations of the statute's rationality that may be offered by litigants or other courts. Rather, those challenging the legislative judgment must convince us

that the legislative facts on which the classification is apparently based could not reasonably be conceived to be true by the governmental decisionmaker.

Id. at 440 U. S. 111.

Applying these principles to the present case, we conclude that appellants have failed to carry the "heavy burden" of demonstrating that the challenged statute is both arbitrary and irrational. Hodel v. Indiana, supra, at 452 U. S. 332. The court below offered the following justification for the distinction drawn between reorganized and nonreorganized districts:

The obvious purpose of [statutes treating reorganized and nonreorganized schools differently] is to encourage school district reorganization with a concomitant tax base expansion and an enhanced and more effective school system. The legislation provides incentive for the people to approve school district reorganization by alleviating parental concerns regarding the cost of student transportation in the reorganized district.

402 N.W.2d at 903. Appellees offer a more elaborate, but not incompatible, explanation:

"[T]he authorization of the bus fee to be charged by districts such as Dickinson has nothing to do with the reorganization of school districts. The reasoning for it is to simply have the few that use the service pay a small portion of that cost in exchange for the substantial benefits received. " "The only reason that the fee authorization was not extended to reorganized districts is that those districts, prior to the passage of the statute permitting fees, were already committed on an individual district basis to some type of transportation system which had been submitted to and approved by the voters in each separate district. To permit the 1979 statute authorizing fees to be retroactively effective in reorganized districts would have been an obvious impairment of existing legal relationships, since the already established transportation systems in the various reorganized districts did not include any authority to charge a fee."

Brief for Appellees 16. The State of North Dakota informs us that the 1979 legislation was proposed to the legislature by the Dickinson School District itself, which had for several years been charging transportation fees and which "became concerned when it appeared that the 1979 Legislature would enact a statute prohibiting charging the fee." Brief for State of North Dakota as Amicus Curiae 6-7 (citations to legislative history omitted). The State's account of the reason for confining the express authorization of fees to nonreorganized schools districts is the same as the account offered by appellees. Id. at 9.

The explanation offered by appellees and the State is adequate to rebut appellants' contention that the distinction drawn between reorganized and nonreorganized districts is arbitrary and irrational. The Supreme Court of North Dakota has said, and the State agrees, that all reorganized school districts are presently required to furnish or pay for transportation for students living as far away from school as Sarita Kadrmas does. See 402 N.W.2d at 903 (citing N.D.Cent.Code § 15-27.3-10 (Supp.1987)); Tr. of Oral Arg. 32. This requirement, however, is not imposed directly by statute, but rather by the reorganization plans that are statutorily required in the reorganization process. With certain specified exceptions (not including the transportation provisions), those reorganization plans may be changed by the voters in the affected districts. N.D.Cent.Code § 15-27.3-19 (Supp.1987). Although it appears that no reorganized district has ever used this mechanism to adopt a user fee like Dickinson's, we have not been informed that such a step could not legally be taken. Thus, the one definitely established difference between reorganized and nonreorganized districts is this: in the latter, local school boards may impose a bus service user fee on their own authority, while the direct approval of the voters would be required in reorganized districts. That difference, however, simply reflects voluntary agreements made during the history of North Dakota's reorganization process, and it could scarcely be thought to make the State's laws arbitrary or irrational.

Even if we assume, as appellants apparently do, that the State has forbidden reorganized school districts to charge user fees for bus service under any circumstances, it is evident that the legislature could conceivably have believed that such a policy would serve the legitimate purpose of fulfilling the reasonable expectations of those residing in districts with free busing arrangements imposed by reorganization plans. Because this purpose could have no application to nonreorganized districts, the legislature could just as rationally conclude that those districts should have the option of imposing user fees on those who take advantage of the service they are offered.

In sum, the statute challenged in this case discriminates against no suspect class and interferes with no fundamental right. Appellants have failed to carry the heavy burden of demonstrating that the statute is arbitrary and irrational. The Supreme Court of North Dakota correctly concluded that the statute does not violate the Equal Protection Clause of the Fourteenth Amendment, and its judgment is

Affirmed.

Notes

* Appellants also suggest that their position is supported by Bearden v. Georgia, 461 U. S. 660 (1983). We disagree. In Bearden, we held that a trial court erred

in automatically revoking probation because the [offender] could not pay his fine, without determining that [he] had not made sufficient bona fide efforts to pay or that adequate alternative forms of punishment did not exist.

Id. at 461 U. S. 662. Whether this decision is considered under equal protection or due process principles, see id. at 461 U. S. 664 -667, the criminal sentencing decision at issue in Bearden is not analogous to the user fee at issue in the case before us.