(concurring). With this decision, the Court begins to cope with the dark side of municipal land use regulation — the use of the zoning power to advance the parochial interests of the municipality at the expense of the surrounding region and to establish and perpetuate social and economic segregation.
The problem is not a new one. Early opponents of zoning advanced the possibility of such abuse as an argument against allowing municipalities the power to zone. See, e. g., Ambler Realty Co. v. Euclid, 297 F. 307, 316 (N. D. Ohio 1924), rev’d 272 U. S. 365, 47 S. Ct. 114, 71 L. Ed. 303 (1926). Later, even those sympathetic to the goals and methods of zoning began to express concern. See, e. g., Haar, “Zoning for Minimum Standards: The Wayne Township Case,” 66 Harv. L. Rev. 1051 (1953). In that spirit, Justice Jacobs wrote for this Court in Pierro v. Baxendale, 20 N. J. 17, 29 (1955):
We are aware of the extensive academic discussion following the decisions in the Lionshead and Bedminster cases, supra, and the suggestion that the very broad principles which they embody may intensify dangers of economic segregation which even the more tradi*194tional modes of zoning entail. * * * In the light of existing population and land conditions within our State these powers may fairly be exercised without in anywise endangering the needs or reasonable expectations of any segments of our people. If and when conditions change, alterations in zoning restrictions and pertinent legislative and judicial attitudes need not be long delayed. ''
The growth of the new suburbs, first as affluent residential communities and, more recently, as sites for commercial and industrial development, leaving persons with low or even moderate incomes housed inadequately in the cities and the older, inner suburbs, far from new sources of employment, magnified the importance of the problem, moving it from the realm of speculation to that of physical and social reality. Justice Hall was among the first to recognize the new significance of the problem in his now classic dissent to Vickers v. Gloucester Tp., 37 N. J. 232, 252 (1962), appeal dismissed 371 U. S. 233, 83 S. Ct. 326, 9 L. Ed. 2d 495 (1963). The facts of this ease, as well as the information compiled by various governmental agencies, of which the Court may take notice, e. g., Nat’l Comm’n on Urban Problems, Building the American City, H. R. Doc. No. 34, 91st Cong. 1st Sess. 211 (1968); N. J. Dept. of Community Affairs, Land Use Regulation: The Residential Land Supply (1972),1 demonstrate that judicial action in this area is long overdue.
Therefore, I join in the thoughtful and eloquent majority opinion of Justice Hall. I differ from the majority only in that I would have the Court go farther and faster in its implementation of the principles announced today. The fact that abuses of the municipal zoning power are now widespread and derive from attitudes and premises deeply ingrained in the suburban planning and zoning processes requires that the Court not restrict itself to the facts of this particular case but, rather, lay down broad guidelines for judicial review of municipal zoning decisions which implicate *195these abuses. Cf. Busik v. Levine, 63 N. J. 351, 363-64 (1973), appeal dismissed 414 U. S. 1106, 94 S. Ct. 831, 38 L. Ed. 2d 733 (1973).
I
The misuse of the municipal zoning power at issue in this case, generieally described as “exclusionary zoning,” see, e. g., BrooTcs, Exclusionary Zoning 8 (Am. Soc’y of Planning Officials 1970), involves two distinct but interrelated practices: (1) the use of the zoning power by municipalities to take advantage of the benefits of regional development without having to bear the burdens of such development; and (2) the use of the zoning power by municipalities to maintain themselves as enclaves of affluence or of social homogeneity.
Both of these practices are improper and to be strongly condemned. They are violative of the requirement, found both in the Constitution of 1947, Art. I, § 1 and the zoning enabling statute itself, N. J. S. A. 40:55-32, that municipal zoning ordinances further the general welfare. Cf. Cresskill v. Dumont, 15 N. J. 238, 247-49 (1954); Duffcon Concrete Products, Inc. v. Cresskill, 1 N. J. 509 (1949). They aré inconsistent with the fundamental premise of the New Jersey zoning legislation that zoning is concerned with the physical condition of the municipality not its social condition. In a deeper sense, they are repugnant to the ideals of the pluralistic democracy which America has become.
The motivation for exclusionary zoning practices are deeply embedded in the nature of suburban development. In part, these practices are motivated by fear of the fiscal consequences of opening the community to all social and economic classes. Residents of the municipality anticipate that higher density development will require the construction of additional roads, sewers, and water systems, the provision of additional municipal services, and the increase of school expenditures, all of which must be financed through local property taxes. Often, although not universally, this is a reasonable concern, *196see generally Sternlieb, Residential Development, Urban Growth and Municipal Costs (1973); N. J. Cty. & Mun. Gov. Study Comm’n, Housing & Suburbs: Fiscal & Social Impact of Multifamily Development (1974), and, as long as these costs are primarily financed through local property taxes, will continue to impel suburban communities to use the zoning laws to encourage commercial development and discourage settlement of less affluent families. But cf. Robinson v. Cahill, 62 N. J. 473 (1973), cert. denied 414 U. S. 976, 94 S. Ct. 292, 38 L. Ed. 2d 219 (1973). Insofar as this fiscal situation prevails, suburban communities will find the temptation of exclusionary zoning alluring.
In addition, exclusionary zoning practices are also often motivated by fear of and prejudices against other social, economic, and racial groups.2 Nat’l Comm. Against Discrimination in Housing, Jobs and Housing: Final Summary Report on the Housing Component, 25-29 (1972). Thus, in a recent survey of suburban municipal leaders, 42.6% identified social and racial conflict as being the chief impact of low and moderate cost subsidized housing on the municipality, while only 21.3% identified fiscal problems as the chief impact. Cty. & Mun. Gov. Study Comm’n, Housing & Suburbs: Fiscal & Social Impact of Multifamily Development, supra at 86. A large proportion felt that even State assumption of the additional municipal costs of a balanced housing policy would not make a great impact on the general unacceptability of low or moderate income housing. Id. at 89. ETor are these attitudes, however disappointing we may find them at this late date, wholly surprising. Many people who settle in suburban areas do so with the specific intention of living in affluent, socially homogeneous communities and of escaping what they perceive to be the problems of the cities. See generally, Clawson, Suburban Land Conversion in the *197United States, 45 (1971). They do not wish their insular communities to be disturbed by the introduction of diverse social, racial, and economic groups. The experience of the nation over the past 20 years must serve as a caution that, however much we might wish it, we cannot expect rapid, voluntary reversal of such attitudes.
Exclusionary zoning may assume a wide variety of forms. Ultimately, the existence of such practices must be measured by exclusionary intent and actual or potential exclusionary effect. Cf. Hawkins v. Shaw, 437 F. 2d 1286 (5 Cir. 1971); Hobson v. Hansen, 269 F. Supp. 401 (D. D. C. 1967), aff'd sub nom. Smuck v. Hobson, 132 U. S. App. D. C. 372, 408 F. 2d 175 (D. C. Cir. 1969). Some zoning devices, however, which are inherently exclusionary in effect or which lend themselves especially readily to abuse have come into wide-spread use and are a revealing gauge of the extent of exclusionary zoning in New Jersey:
1) Minimum house size requirements
As of 1970, 92% of the land in the Department of Community Affairs study area3 zoned for single family housing was covered by some minimum house size requirement. More than 65% was zoned for houses with 1,000 square feet or more of floor space, and 38.9% for houses of 1,200 square feet or more. By contract, the controversial case of Lionshead *198Lake v. Wayne Tp., 10 N. J. 165 (1953), appeal dismissed 344 U. S. 919, 73 S. Ct. 386, 97 L. Ed. 708 (1953), upheld a miuimum of 768 square feet in all districts. There is wide variation from county to county and within the various counties.4 In the so-called “outer-ring” counties in northern New Jersey — Morris, Somerset, Middlesex, and Monmouth5 — houses of less than 1,000 square feet may be built on only about 10% of the land zoned for single family dwellings. On 77% of the land zoned for single family dwellings,- houses must have 1,200 square feet or more of floor space. In the South Jersey outer-ring counties, Burlington, Camden, and Gloucester, the figures are 31.9% and 43.5% respectively.
The effect on the cost of housing of such requirements is obvious. If one assumes construction costs of $20 per square foot of floor space,6 a 1,000 square foot minimum imposes a corresponding minimum figure of $20,000 upon the portion of the cost of a new house attributable to construction. A recent *199study of housing costs indicates that floor space is the single most important factor contributing to differences in prices for new housing, even more important than the socio-economic status of the municipality. Sagalyn & Sternlieb, supra at 48. 2) Minimum lot size and minimum frontage requirements
On two-thirds of the land in the Department of Community Affairs study area zoned in 1970 for single family dwellings, houses could not be built on lots of less than an acre. Upon only 5.1% could houses be built on 10,000 square feet or less. Approximately 10% of such land in the outer-ring counties in South Jersey was zoned for 10,000 square foot lots or less; 45.9% was zoned for an acre or more. In the North Jersey outer-ring counties only 1.2% of the land zoned for single family dwellings was available for use as lots of 10,000 square feet or less; 77% was zoned for one acre or larger lots. Here, too, there are wide variations among counties. In Camden, 24.5% of the land was zoned for lots of 10,000 square feet or less, and less than 34% for lots of an acre or more. In Somerset County, only .2% of the land was zoned for lots of 10,000 square feet or less; 85.3% was zoned for lots of an acre or more, and 24.6% was zoned for three acres or more. By way of comparison, the American Public Health Association, a vigorous advocate of high minimum standards, recommends 6,000 square feet as a suitable minimum lot size based upon health considerations. Am. Public Health Ass’n, Planning the Neighborhood, 37 (1948).
Minimum frontage requirements frequently, although not invariably, are found together with minimum lot size requirements. The Residential Land Supply at 21-24. Only 13.5% of the land zoned in 1970 for single family housing in the Department of Community Affairs study area was zoned for 100 foot minimum frontage or less. In that area, 54.3% was zoned for 150 feet or more. This device was widely used in the northern outer-ring counties, where only 5% of the land is zoned for less than 100 foot frontage and 68.4% is zoned for more than 150 feet, but somewhat less widely used in the southern outer-ring counties, where 22.7% of *200the land was zoned for less than 100 foot frontage and 42.5% was zoned for more than 150 feet.
Analysis of the exclusionary impact of the widespread use of minimum lot size and minimum frontage requirements is a more complex task than that of analyzing minimum building requirements. See generally, Building the American City, supra at 213-15; Williams & Norman, supra at 493-97; Sagalyn & Sternlieb, supra at 6-16, 66-67. There is a significant correlation between lot size and price of housing in areas without sewage service and between frontage and price in areas with sewage service. Sagalyn & Sternlieb, supra at 54-56. At the very least, it can be said with certainty that extensive mapping for large lots or large lot widths drives up the cost of smaller lots and thereby significantly raises the overall price of housing. Williams & Norman, supra at 496-97.
3) Prohibition of multifamily housing
Realistically, much of the housing needs of persons with low or moderate incomes will have to be met through various forms of multifamily housing. Williams & Norman, supra at 481. Hence, restrictions upon the construction of such housing have a highly exclusionary effect. In the Department of Community Affairs study area, construction of multifamily housing was permitted on only 6.2% of the land zoned for residential uses. If six aberrant rural municipalities are disregarded, the percentage falls to 1.1%.7 In the South Jersey outer-ring counties, 2.7% of such land is zoned for multifamily housing; in the northern outer-ring counties, only of 1% is so zoned. There is no land zoned for multi*201family housing in Somerset County and only .006% is so zoned in Monmouth County.8
4) Bedroom restrictions
The effect of zoning against multifamily dwellings is magnified by restrictions upon the number of bedrooms which may be included in each dwelling unit. In the Department of Community Affairs study area9 59% of the already limited area of land zoned for multifamily dwellings is restricted to one-bedroom or efficiency apartments. On only 20.4% of this land is construction of apartments of three or more bedrooms permitted. In addition, in many areas where some construction of larger apartments is permitted, they are limited to a small percentage of any individual development. The Residential Land Supply, supra at 11. In the North Jersey outer-ring counties, 78% of the land zoned for multifamily housing is burdened with bedroom restrictions. In the South Jersey outer-ring counties, 83% of the land zoned for multifamily housing is so restricted. The situation is particularly acute in Burlington County, where 95.8% of the land zoned for multifamily housing has bedroom restrictions.
The Department of Community Affairs concluded from these figures that:
*202* * * [I]n general, the multi-family zoned land is geared to accommodate the housing needs of single people, married couples without children, and retired people, and not geared to the housing needs of the large part of the population living as families with children. [The Residential Land Supply, supra at 12; footnote omitted],
5) Prohibition of mobile homes
Mobile homes offer an alternate, less expensive form of housing. They have long since ceased to be mere “house trailers” but have become an important form of mass produced semi-permanent housing. Indeed, for many persons they may be the only form of new housing available. However, only .1% of the land zoned for residential use in the Department of Community Affairs study area was zoned for use by mobile homes. In the South Jersey outer-ring counties, .3% of the residential land was so zoned, the bulk of it being in Gloucester County, which had twice as much land zoned for mobile homes as the rest of the study area combined. None was zoned for this purpose in Camden County. No land was zoned for mobile homes in the northern outer-ring counties.10
6) Ov&rzoning for nonresidential uses
Zoning a great proportion of the developable land in a municipality noncumulatively for nonresidential uses may have the effect of forcing the price of land zoned for residential purposes up beyond the reach of persons with low or moderate incomes. Neither statewide nor countywide figures provide unambiguous evidence of the use of such practice at present in New Jersey. Land Use Regulation, supra at 6-8; Sagalyn & Sternlieb, supra at 96. At the municipal level, the use of such practices is more evident in some areas. Thus, in Mt. Laurel itself, 29.2% of the land in the township, totaling 4,121 acres, is zoned for industrial uses, although *203only 100 acres within the township has actually been developed for such use in the past 10 years, and there is no reasonable prospect of industrial rises expanding to such proportions.
If anything, these figures underestimate the extent of exclusionary zoning in this State. A wide variety of other techniques may be used to achieve an exclusionary effect. In addition, a municipality need not use all of these techniques to achieve exclusionary ends. Municipalities which have large lot-size and frontage requirements may not have building-size requirements and vice versa. Thus, only 18% of the land in the Department of Community Affairs study area zoned for single family residences permitted houses with less than 1,200 square feet of floor space to be constructed on a acre or less site with 100 foot or less frontage.
Forceful judicial intervention is necessitated not only by the already widespread use of exclusionary zoning practices and by the fact that the motivations for such are deeply ingrained in the suburban zoning and planning process,' but also by certain extrinsic factors of which the Court may take notice.
First, the United States suffers from an acute national housing shortage. It has been estimated that over 10 million dwelling units would be needed to provide each family in the country with adequate housing. Building the American City, supra at 75. In New Jersey, it has been estimated that there is an immediate need for over 400,000 dwelling units. Dep’t of Community Affairs, The Housing Crisis in New Jersey, 1970 (1970).11 New Jersey, already the second most densely populated state in the country, is experiencing continuing population growth — it is estimated that by 1985 the total population will have increased from its 1970 figure of 7,200,000 to about 10,000,000. Special Message to the Legislature by Governor Cahill, A Blueprint for Housing in New *204Jersey, Dec. 7, 1970, at 1. Housing, particularly in urban areas, is deteriorating. The percentage of substandard units throughout the State increased from 14.8% in 1960 to 17.4% in 1969. In Hudson County, the increase was from 22.3% to 31.3%. Housing Crisis in New Jersey, supra at 14. Some of these units dropped out of the housing market altogether. It has been estimated that simply to keep up with population growth and to replace units which drop out of the housing market, 100,000 new units would have to be constructed in the State each year. Special Message to the Legislature by Governor Cahill, A Blueprint for Housing in New Jersey, Dec. 7, 1970, at 1. In fact, the construction of new housing in the State peaked in 1964, when permits were issued for the construction of 68,078 units, and has declined steadily since then. In 1970, permits were issued for construction of only 39,897 units. Sagalyn & Sternlieb, Zoning & Housing Costs, 98 (1972).
The brunt of this shortage is, of course, borne by persons with low or moderate incomes. As of 1970, it was estimated that not only were half of all low income families in the State obliged to live in inadequate housing, but so were approximately 125,000 families with moderate incomes. Housing Crisis in New Jersey, supra at iv. The median cost of a new single family detached house was $30,000 in the northeastern region of the country in 1969. Sagalyn & Sternlieb, supra at 20. Prices since then have risen precipitously. A study made in 1971 found median new house costs in suburban counties to range from $33,263 in Burlington to $62,500 in Somerset and $67,000 in Bergen. Id. at 22. Such 'housing was effectively beyond the reach of families with incomes of less than $15,000 per year. Housing Crisis in New Jersey, supra at 42. As of the time of that study, the median family income in New Jersey was $11,407 per year. Analyses by both the federal and state governments, Building the American City, supra at 93; Housing Crisis in New Jersey, supra at 40-43, indicate that the majority of families can afford to neither rent nor buy new housing at current prices. Other *205authorities estimate that such housing may be beyond- the financial capacity of as much as ¿4 of all the families in the State, Sagalyn & Sternlieb, supra at 64, and as much as 90% of those families in 'which the head of the household is below the age of 35. Nat'l Comm. Against Discrimination in Housing, Housing and Jobs: Final Summary Report on the Sousing Component, supra at 22. In theory, low and moderate income families should benefit even from construction of new housing which they themselves cannot afford because such housing creates vacancies which “filter down.” In reality, however, most of these vacancies are absorbed by the enormous lag between population growth and new housing construction. Sagalyn & Sternlieb, supra at 42. The housing which does “filter down” to persons with low or moderate incomes is often badly dilapidated and in deteriorating neighborhoods. Building the American City, supra at 11; Clawson, Suburban Land Conversion in the United States, 330 (1970).
The existence of this housing shortage has been amply recognized by all branches of government in this State. See, e. g., Inganamort v. Borough of Fort Lee, 62 N. J. 521 (1973); N. J. Mortgage Finance Agency v. McCrane, 56 N. J. 414 (1970); Marini v. Ireland, 56 N. J. 130 (1970) ; Mortgage Finance Agency Law, N. J. S. A. 17:1B-5 (L. 1970, c. 38); Department of Community Affairs Demonstration Grant Law, N. J. S. A. 52:27D-61 (L. 1967, c. 82); Special Message to the Legislature by Governor Cahill, A Blueprint for Sousing in New Jersey, Dec. 7, 1970; Special Message to the Legislature by Governor Cahill, New Sorizons in Sousing, Mar. 27, 1972.
Second, the growing movement of commerce and industry to the suburbs is imposing a heavy burden upon employees who are unable to obtain housing in these suburban areas. The trend, which began after World War II and has continued unabated, arises from a variety of causes — need for additional land for expansion, automated methods of handling goods which make single-floor layout of manufacturing plants economically desirable, increased access pro*206vided by superhighways, desire for aesthetic surroundings, lower suburban property taxes, etc. See generally, Clawson, Suburban Land Conversion in the United States, 40 (1971). Retail establishments have also relocated in the suburbs, taking advantage of the shift in the affluent population, the access provided by suburban highways, and the more attractive surroundings. Id. at 40-41. The result has been a shift of blue-collar jobs from the cities to the suburbs. Id. at 40. Thus in the New York metropolitan region,12 75% of the 990,000 new jobs created between 1959 and 1967 were located outside of New York City. Jobs at manufacturing production sites outside New York City increased during that period by 138,440, while such jobs within New York City diminished by 47,110. Of the 100,600 new jobs created in retailing between 1959 and 1965, 95% were located outside of New York City. The new jobs created within New York City in recent years have been confined almost exclusively to services, finance, insurance, communications, utilities, government and manufacturing headquarters offices, all of which are fields with high percentages of white-collar employment. It appears that these trends will continue into the foreseeable future. It has been estimated that between 1970 and 1985 New York City will lose another 137,700 factory jobs, and the suburbs gain 122,700. Nat'l Comm. Against Discrimination in Housing, Jobs and Housing, 6-9 (1970). Job movement in the Philadelphia metropolitan region displays an essentially identical pattern. Nat’l Comm. Against Discrimination in Housing, Impact of Housing Patterns on Job Opportunities, 21-26 (1968). This is, of course, the natural and foreseeable consequence of “fiscal zoning” that encourages the development within a municipality of commercial establishments, which are net tax-providers, and discourages the development of housing for per*207sons who would work in such establishments, on the grounds that they are net revenue-absorbers.
This trend is one that imposes unfair burdens on the worker who is locked out of suburban residential areas. For blue-collar workers, commutation from the cities to suburban job locations is both time-consuming and prohibitively expensive. There is often no access at all by public mass transit and even when such transportation is available in theory it is frequently impractical in fact. Nat’l Comm. Against Discrimination in Housing, The Impact of Housing Patterns on Job Opportunities, supra at 27-30; Nat’l Comm. Against Discrimination in Housing, Jobs and Housing, supra at 23-26. See generally, Babcock and Bosselman, Exclusionary Zoning: Land Use Requlation in the 1970s, 114-15 (1973).
Third, even as we write, development proceeds apace. Once an area is developed, it becomes much more difficult to alter its social and economic character. There is a hazard that prolonged judicial inaction will permit exclusionary practices to continue to operate and will allow presently developing communities to acquire permanent exclusionary characteristics. The concern is not that New Jersey will soon be without developable land, but that large areas now in the process of development will have already acquired irrevocably exclusionary characteristics before the courts effectively intervene. Thus, the Delaware Yalley Regional Planning Commission has estimated that the amount of developed land in the Philadelphia metropolitan area (including Burlington, Camden, Gloucester, and Mercer Counties) will increase by 38% between 1960 and 1985, Clawson, supra at 294, and the Regional Plan Association has estimated that intensive land use in the New York metropolitan area (which includes most of northern New Jersey) will double in the same period, Clawson, supra at 279.
Finally, we must take notice of the fact that the cost of building new housing has increased steadily over the past 10 years, and shows all signs of continuing to increase in *208the future. Between 1963 and 1969, the median sales price of new single-family housing in the northeastern part of the United States rose from $20,000 to $30,500. Sagalyn & Sternlieb, supra at 20. The costs of building rental housing had increased comparably. See generally, Clawson, supra at 82-83. As the costs of housing slip farther beyond the reach of persons of low and moderate incomes, the practical valué of zoning reform diminishes and becomes increasingly contingent on the establishment of new State and federal housing subsidy programs.
Today’s decision by its terms expressly concerns exclusionary zoning practices in municipalities which are developing but which “still are not completely developed and remain in the path of inevitable future residential, commercial and industrial demand and growth.” Ante at 160. As to these communities, the Court holds:
* * * [E]very such municipality must, by its land use regulations, presumptively make realistically possible an appropriate variety and choice of housing. More specifically, presumptively it cannot foreclose the opportunity of the classes of people mentioned for low and moderate income housing and in its regulations must affirmatively afford that opportunity, at least to the extent of the municipality’s fair share of the present and prospective regional need therefor. These obligations must be met unless the particular municipality can sustain the heavy burden of demonstrating peculiar circumstances which dictate that it should not be required so to do. I Ante at 174; footnote omitted].
The majority has chosen not to explore in this case either the extent of the affirmative obligations upon developing municipalities or the role of the courts in enforcing those obligations. It has also chosen not to consider the degree to which the principles applicable to developing municipalities are also applicable to rural ones and to largely developed ones. The facts set out above seem to me to demonstrate that exclusionary zoning is a problem of such magnitude and depth as to require that the Court extend these principles to all municipalities in the State, recognizing, of *209course, that they may have different implications for municipal conduct when applied in different areas, and that the Court establish a policy of active judicial enforcement, not only of the negative obligations imposed upon municipalities by this decision but also of the affirmative obligations.
II
I consider first the extent of the affirmative obligation to plan and provide for housing opportunities for persons with low and moderate incomes that municipalities assume when they choose to avail themselves of land use controls permitted by statute. Although this discussion will concern itself initially with developing municipalities, many of the same considerations also apply mutatis mutandi to developed municipalities and rural areas, as will subsequently become clear.
A municipality need not exercise at all the powers permitted it by the zoning and planning statutes, N. J. S. A. 40:55-30 et seq. and N. J. S. A. 40:55-1.1 et seq.13 Once, however, it chooses to enter the field of land use regulation it assumes a duty — one of constitutional dimensions, deriving from N. J. Const. (1947), Art. I, § 1 — to act affirmatively to provide its fair share of the low and moderate income housing necessary to meet the regional housing needs. Cf. Southern Alameda Spanish Speaking Organization v. Union City, 424 F. 2d 291, 295-6 (9 Cir. 1970); Williams, American Planning Law: Land Use and the Police Power §§ 66.15, 66.16 (1974).
The substantive content of this affirmative obligation will necessarily vary from municipality to municipality, depend*210ing upon, among other things, the intensity of the regional housing needs, the extent of previous exclusionary practices by the municipality, and the degree to which the municipality is benefiting, directly or indirectly, from; regional economic development. A factor of special importance is the sufficiency of local housing opportunities for persons who might fill jobs created by new commercial and industrial development in the locality. Cf. Building the American City, supra at 243; ALI, Model Land Development Code, § 7-405 (Ten. Draft No. 3, 1971); Babcock & Bosselman, Exclusionary Zoning: Land Use Regulation and Housing in the 1970s, 114-15 (1973).
Every developing municipality has at least a duty to consider regional housing needs in all its planning activities, both formal and informal, including its formulation of the comprehensive plan underlying its zoning ordinance, N. J. S. A. 40:55-21, its adoption of a master plan, N. J. S. A. 40:55-1.10 and its consideration of applications for zoning variances, N. J. S. A. 40:55—39, and for approval of subdivision plats, N. J. S. A. 40:55-1.14.14 In addition, since effective planning for regional needs is virtually impossible without some degree of intergovernmental cooperation, all developing municipalities also have an affirmative obligation to cooperate, where appropriate, in regional planning efforts, to cooperate, for example, with regional planning boards established pursuant to N. J. S. A. 40:27-9 and in area review procedures established under the Intergovernmental Cooperation Act, 42 U. S. C. 4231 and implemented by U. S. Office of Management and Budget Circular A-95 (July 24, 1969) and N. J. A. C. 5:42-1.1 et seq. See generally Babcock & Bosselman, Exclusionary Zoning: Land Use Regulation and Homing in the 1970s, 135-47 (1973).
*211There is little hope that the private housing construction industry will be able to satisfy the State’s housing needs in the foreseeable future, even if all exclusionary barriers are Temoved. Building the American City, supra at 93. To meet these needs, State or federal assistance will be required. This fact has been recognized by both the State Legislature and Congress in a lengthy series of statutes providing governmental subsidies for private construction and ownership of low and moderate income housing. See, e. g., Housing and Community Development Act of 1974, 88 Stat. 633 (codified at various places in 12, 42 U. S. C.); National Housing Act of 1959, § 303, as amended, 12 U. S. C. 1701q; National Housing Act, §§ 335, 336, as amended, 12 U. S. C. 1715z, 1715z-1 et seq.; Mortgage Einance Agency Law, N. J. S. A. 17:1B-4 et seq.; Housing Einance Agency Law, N. J. S. A. 55:14J-1 et seq.; Department of Community Affairs Demonstration Grant Act, N. J. S. A. 52:27D-59 ei seq. To a greater or lesser degree, all of the programs require active municipal cooperation. Eailure to actively cooperate in the implementation of such programs as effectively thwarts the meeting of regional needs for low and moderate income housing as does outright exclusion. See, e. g., Farmworkers of Florida Housing Projects, Inc. v. Delray Beach, 493 F. 2d 799 (5 Cir. 1974); Kennedy Park Homes Ass’n v. Lackawanna, 318 F. Supp. 669 (W. D. N. Y. 1970), aff’d 436 F. 2d 108 (2 Cir. 1970), cert. den. 401 U. S. 1010, 91 S. Ct. 1256, 28 L. Ed. 2d 546 (1971). Developing municipalities have a duty to make all reasonable efforts to encourage and facilitate private efforts to take advantage of these programs.
Finally, there may be circumstances in which the municipality has an affirmative duty to provide housing for persons with low and moderate ineomes through public construction, ownership, or management. See, e. g., Community Development and Housing Act of 1974, Title II, 42 U. S. C. 1401 et seq.; Local Housing Authority Law, N. J. S. A. *21255:14A-1; cf. Mahaley v. Cuyahoga Metropolitan Housing Authority, 355 F. Supp. 1257 (N. D. Ohio 1973) rev’d 500 F. 2d 1087 (6 Cir. 1974), cert. den. 419 U. S. 1108, 95 S. Ct. 781, 42 L. Ed. 2d 805 (1975).
There are certain important limitations on the scope of these affirmative obligations. While municipalities must plan and provide for regional housing needs, no municipality need assume responsibilty for more than its fair share of these needs. The purpose of land use regulation is to create pleasant, well-balanced communities, not to recreate slums in new locations. It is beyond dispute, that when the racial and socioeconomic composition of the population of a community shifts beyond a certain point, the white and affluent begin to abandon the community. While the attitudes underlying this “tipping” effect must not be catered to, the phenomenon must be recognized as a reality. See, e. g., Graves v. Romney, 502 F. 2d 1062 (8 Cir. 1974), cert den. - U. S. -, 95 S. Ct. 1354, 43 L. Ed. 2d 440 (1975); Otero v. New York City Housing Authority, 484 F. 2d 1122 (2 Cir. 1973). Municipalities have a legitimate interest in placing an upper limit on the extent of uses which, if permitted to expand without limit, might reasonably be feared to operate to the general detriment. Tidewater Oil Co. v. Carteret, 84 N. J. Super. 525 (App. Div. 1965), aff’d 44 N. J. 338 (1965). The limitation of the municipality’s affirmative duty to one of providing for its fair share of reasonable needs responds to this interest. Cf. Mass. Gen. Laws Ann., c. 40B, §§ 20-23 (a statute authorizing the state to override local zoning restrictions for low and moderate income housing projects, but limiting the municipality’s obligations to fixed annual and total maxima). A number of regions have, in response to the problem of exclusionary zoning, voluntarily sought to put such fair share housing plans into effect. See Babcock & Bosselman, supra at 109-13.
Nor need a municipality altogether give up control of the pace and sequence of development. A municipality has *213a legitimate interest in insuring that residential development proceeds in an orderly and planned fashion, that the burdens upon municipal services do not increase faster than the practical ability of the municipality to expand the capacity of those services, and that exceptional environmental and historical features are not simply concreted over. See, e. g., Golden v. Ramapo Planning Board, 30 N. Y. 2d 359, 334 N. Y. S. 2d 138, 285 N. E. 2d 291 (1972), appeal dismissed 409 U. S. 1003, 93 S. Ct. 436, 34 L. Ed. 2d 294 (1972); Construction Industry Ass’n of Sonoma County v. Petaluma, 375 F. Supp. 574 (N. D. Cal. 1974); Mass. Gen. Laws Ann., c. 40B, §§ 20, 23.15 On the other hand, such regulations must be reasonable, substantially related to the purpose which they seek to achieve, and must adopt the least exclusionary means practical. “Zoning is a means by which a governmental body can plan for the future — it may not be used as a means to deny the future.” National Land and Investment Co. v. Kohn, 419 Pa. 504, 528, 215 A. 2d 597, 610 (Pa. Sup. Ct. 1965). By way of illustration, large lot zoning is commonly rationalized as a device for preventing premature development. Such zoning, it is claimed, merely creates holding zones. In practice, however, it appears that land zoned for large lots, even where intended as an interim holding zone, tends to become frozen in a pattern of low density development. Williams & Norman, supra at 495. Such zoning is not a reasonable device for regulating the pace and sequence of development. Its effects on development, if any, are merely exclusionary.
Finally, the affirmative duty to plan and provide for regional needs does not require the municipality to make any specific piece of property available for low or moderate income housing, absent a showing that there are inadequate alternative sites realistically available for that type of de*214velopment. A municipality must zone in accordance with a comprehensive plan. N. J. S. A. 40:55-32. Once it has adopted a comprehensive plan which properly provides for the community’s fair share of the regional housing needs, it is entitled to be able to enforce that plan through its zoning ordinances. To permit a developer to com,e in at a later date and demand, as a matter of right, that a piece of property not presently zoned to permit development of low or moderate cost housing be so zoned, is to undermine the entire premise of land use regulations. Williams, supra at § 66.15; see Confederation de la Raza Unida v. Morgan Hill, 324 F. Supp. 895 (N. D. Cal. 1971). The one exception to this principle is the situation in which the developer can show that, as a matter of practical fact, sufficient land is not available for development in the areas zoned for low or moderate income housing. See, e. g., Kennedy Park Homes Association v. Lackawanna, 318 F. Supp. 669 (W. D. N. Y. 1970), aff’d 436 F. 2d 108 (2 Cir. 1970), cert. den. 401 U. S. 1010, 91 S. Ct. 1256, 28 L. Ed. 2d 546 (1971) (construction of multi-family housing in area zoned for it would perpetuate a segregated housing pattern and add to existing problem of overcrowding); Pascack Ass’n v. Washington Tp., 131 N. J. Super. 195 (Law Div. 1974) (area zoned for multi-family housing was already largely occupied by other, non-residential uses, and was burdened with other zoning requirements that made construction of low or moderate income housing impractical).
The affirmative obligations of developing municipalities so far discussed are legally binding and judicially enforceable. It is a truism that courts have no inherent expertise in matters of land use planning. They are not equipped to sit as higher planning boards and substitute their judgment for municipal bodies lawfully established for the purpose of making planning and zoning decisions. Bow & Arrow Manor v. West Orange, 63 N. J. 335, 343 (1973); Kozesnik v. Montgomery Tp., 24 N. J. 154, 167 (1957). The decision as to *215how the municipality should go about performing the affirmative duties set out above is one initially to be made by the officials of the municipality itself. Nevertheless, if the municipality has failed to take affirmative steps to make realistically possible a variety and choice of housing so as to meet its fair share of the regional housing needs, its actions are presumptively illegal and the burden shifts to the municipality to justify them. The mere fact that local land use control issues are involved does not preclude the court from making such determinations, nor, if a court finds that the municipality has failed to meet its obligation, from exercising the full panoply of equitable powers to remedy the situation. Norwalk CORE v. Norwalk Redevelopment Agency, 395 F. 2d 920 (2 Cir. 1968); Hawkins v. Shaw, 437 F. 2d 1286 (5 Cir. 1971); Pascack Ass’n v. Washington Tp., 131 N. J. Super. 195 (Law Div. 1974).
Judicial enforcement of municipal obligations, both negative and affirmative, to plan and provide for a fair share of regional housing needs, even if only directed to one municipality, necessarily has grave implications for the entire region. In dealing with such cases courts must act both deliberately and imaginatively. In administering such relief the trial court ought to proceed in four steps:
(1) identify the relevant region;16
(2) determine the present and future housing needs of the region;
(3) allocate these needs among the various municipalities in the region;17 and
*216(4) shape a suitable remedial order.
Cf. Williams, American Planning Law: Land Use and the Police Power § '66.38 (1974). Needless to say, all of these steps involve difficult factual determinations based upon expert testimony and statistical evidence. It may well be appropriate for the court to appoint independent experts or consultants for its assistance, see Pascack Ass’n v. Washington Tp., 131 N. J. Super. 195 (Law Div. 1974); cf. Handleman v. Marwen Stores Corp., 53 N. J. 404 (1969); Polulich v. J. G. Schmidt Tool Die & Stamping Co., 46 N. J. Super. 135 (Cty. Ct. 1957); Manual for Complex Litigation, Pt. 1 §§ 1.42, 1.46, 2.60, 3.40 (1973), or to invite participation by the Department of Community Affairs as amicus curiae.
Since conflicting decisions within a given region would be highly undesirable, all municipalities in the region should be joined as parties at the earliest practical point in the proceedings, if not at the instance of one of the parties, then on the motion of the court. R. 4:28-1, 4:30.
*217The trial court must be flexible aud imaginative in molding remedies to fit the facts of each case, balancing the need to vindicate the rights of persons who have been or will be deprived of the opportunity for decent housing if no relief is granted against the principle of local decision-making in land use planning matters. Pascack Ass’n v. Washington Tp., supra; see e. g., Kennedy Park Homes Ass’n v. Lackawanna, 318 F. Supp. 669 (W. D. N. Y. 1970) aff’d 436 F. 2d 108 (2 Cir. 1970) cert. den. 401 U. S. 1010, 91 S. Ct. 1256, 28 L. Ed. 2d 546 (1971); Mahaley v. Cuyahoga Metropolitan Housing Authority, 355 F. Supp. 1257 (N. D. Ohio 1973) rev'd on other grounds, 500 F. 2d 1087 (6 Cir. 1974), cert. denied 419 U. S. 1108, 95 S. Ct. 781, 42 L. Ed. 2d 805 (1975); United Farmworkers of Florida Housing Projects, Inc. v. Delray Beach, 493 F. 2d 799 (5 Cir. 1974); Lakewood Homes, Inc. v. Lima Bd. of Adjustment, 23 Ohio Misc. 211, 52 Ohio Op. 2d 213, 258 N. E. 2d 470 (Ohio Ct. C. P. 1970); mod. 25 Ohio App. 2d 125, 267 N. E. 2d 595 (Ohio Ct. App. 1971).
Ill
It can hardly be denied that there are some suburban municipalities which have already developed in an exclusionary mold. These communities, which have benefited from regional development, have, by their land use controls, contributed to the regional housing shortages. Cf. United States v. Black Jack, 372 F. Supp. 319 (E. D. Mo. 1974). It would be both highly inequitable to absolve them of any responsibility for solving those problems and inconsistent with the legal analysis developed by the Court today. Although the majority does not reach this issue in the present case, I would hold that developed suburban municipalities which have availed themselves of the land use controls permitted by statute and which have not provided sufficient opportunities for development of low and moderate income housing to meet their fair share of regional needs, have both *218a negative obligation not to use zoning and subdivision controls to obstruct the construction of such housing and an affirmative duty to plan and provide for such housing, insofar as these obligations can be carried out without grossly disturbing existing neighborhoods. It is, of course, neither practical nor wise to demand that such communities completely rezone established neighborhoods; to do so would in all likelihood contribute to neighborhood instability and permit certain property owners and developers to obtain windfalls rather than actually effecting construction of low or moderate income housing.
Occasions, however, arise in every community when land becomes available for development or redevelopment. It is on these occasions that these obligations come into play most strongly. Thus the existence of an unmet regional need for low and moderate income housing in appropriate cases must be given great weight in considering applications for variances under N. J. S. A. 40:55-39(d) to permit the construction of such housing. De Simone v. Greater Englewood Housing Corp. No. 1, 56 N. J. 428 (1970); Brunelti v. Madison Tp., 130 N. J. Super. 164 (Law Div. 1974).
The discussion above of judicial enforcement applies equally to developed suburban communities, save only that in formulating relief the trial judge must be alert to take into consideration the delicacy and difficulty of altering the character of already developed areas.
IV
Substantial portions of New Jersey are neither experiencing a surge of development nor situated in the imminently foreseeable path of development. These include much of Cape May, Cumberland, and Salem Counties, portions of Atlantic, Ocean, Sussex and Warren Counties, and some rural areas in other parts of the State. In these municipalities, it is not meaningful to speak of failure to meet regional housing needs, not because there are no persons who are inadequately *219housed,18 but because it is not yet meaningful to speak of “regional” needs nor is it clear that land use controls play a significant role in the housing shortage at the present time. Nevertheless, the time may well come when the frontiers of suburbia will reach these areas. Municipalities may not act to deter the future development of a diversified housing stock by establishing land use controls which are inherently exclusionary and which bear no substantial relationship to any legitimate zoning purpose.
Without purporting to exhaust the list of zoning devices which are presumptively objectionable, I would note that minimum house size requirements which bear no substantial relationship to health needs 19 and requirements as to the minimum or maximum number of bedrooms which a dwelling unit may contain, cf. Molino v. Glassboro, 116 N. J. Super. 195 (Law Div. 1971), are presumptively invalid. Zoning for excessively large lots and large frontages presents more difficult analytic problems, cf. Steel Hill Development, Inc. v. Sanbornton, 469 F. 2d 956 (1 Cir. 1972), but excessive mapping for such lots is, absent extraordinary environmental factors, also presumptively invalid. Cf. Williams & Norman, supra at 496-97.
These obligations, too, are judicially enforceable, albeit without need for the more elaborate procedures appropriate for litigation concerning developing and developed areas which are discussed above.
*220Y
The problems we begin to face today are of awesome magnitude and importance, both for New Jersey and for the nation as a whole. It will not do to approach them gingerly; they call out for forceful and decisive judicial action.
The flow of low and moderate income persons is toward urban areas, hut the cities have neither the space nor the resources to house these people. The question is whether the suburbs will act to accommodate this growth in an orderly way or will simply and blindly resist. Two well-entrenched zoning objectives, low density land use and favorable fiscal balance, though sometimes at odds with each other, have on the whole cooperated to create a milieu of discriminatory zoning which threatens to make the next 30 years of suburban growth a disaster.
The shape of the possible disaster can now be foreseen. The inevitable alternative to assumption by suburban communities of an obligation to provide for their fair share of regional housing needs is an increase in the size of slums with all their attendant miseries. The consequences of such economic, social, and racial segregation are too familiar to need recital here. See Nat'l Advisory Comm’n on Civil Disorders, Report (1968). Justice must be blind to both race and income.
It is not the business of this Court or any member of it to instruct the municipalities of the State of New Jersey on the good life. Fevertiheless, I cannot help but note that many suburban communities have accepted at face value the traditional canard whispered by the “blockbuster”: “When low income families move into your neighborhood, it will cease being a decent place to live.” But as there is no difference between the love of low income mothers and fathers and those of high income for their children, so there is no difference between the desire for a decent community felt by one group and that felt by the other. Many low income families have learned from necessity the desirability of community involve*221ment and improvement. At least as well as persons with higher incomes, they have learned that one cannot simply leave the fate of the community in the hands of the government, that things do not run themselves, but simply run down.
Equally important, many suburban communities have failed to learn the lesson of cultural pluralism. A homogeneous community, one exhibiting almost total similarities of taste, habit, custom and behavior is culturally dead, aside from being downright boring. New and different life styles, habits and customs are the lifeblood of America. They are its strength, its growth force. Just as diversity strengthens and enriches the country as a whole, so will it strengthen and enrich a suburban community. Like animal species that over-specialize and breed out diversity and so perish in the course of evolution, communities, too, need racial, cultural, social and economic diversity to cope with our rapidly changing times.
Einally, many suburban communities have failed to recognize to whom the environment actually belongs. By environment, I mean not just land or housing, but air and water, flowers and green trees. There is a real sense in which clean air belongs to everyone, a sense in which green trees and flowers are everyone’s right to see and smell. The right to enjoy these is connected to a citizen’s right to life, to pursue his own happiness as he sees fit provided his pursuit does not infringe another’s rights.
The people of New Jersey should welcome the result reached by the Court in this case, not merely because it is required by our laws, but, more fundamentally, because the result is right and true to the highest American ideals.
Mountain and P ashman, JJ., concurring in the result.
For modification — Chief Justice Hughes and Justices Jacobs, Hall, Mountain, Sullivan, Pashman and Clifford — 7.
Opposed — None.
Hereinafter cited as Building the American City and The Residential Land Supply, respectively.
Defendant contends that no such motivation is at work in this case. I, like my brethren, accept that claim.
The Department of Community Affairs surveyed the use of exclusionary devices in municipal zoning laws as of 1970. The study area included all developable land in New Jersey except that in Atlantic, Cape May, Cumberland, Hudson, and Salem Counties and in the Hackensack Meadowlands District. The Residential Land Supply, supra. All figures in this opinion as to the extent of use of various zoning provisions are based on that study. For other analyses of Department of Community Affairs data, see Special Message to the Legislature by Governor Cahill, A Blueprint for Housing in Heno Jersey, Dec. 7, 1970; Williams & Norman, “Exclusionary Land Use Controls: The Case of North-eastern New Jersey,” 22 Syracxise L. Rev. 476 (1971) ; Sagalyn & Sternlieb, Zoning and Housing Costs, 93-115 (1972) ; Nat’l Comm. Against Discrimination in Housing, Jobs and Housing: Final Summary Report on the Housing Component, supra at 25-37.
The extreme case is Morris County, where 87% of the land zoned for single family housing had a 1,200 square foot minimum floor space requirement and 66.3% had a 1,600 square foot or more minimum. In Burlington, only 54.7% was zoned for 1,000 square feet or more and 24'% had no minimum house size requirement at all.
The term “outer-ring” is used here in the same sense as it is used in the majority opinion, ante at 162. See Williams & Norman, supra at 479. It should be noted that this term is not used consistently by professional planners. The Regional Plan Association, the principal New York planning group, describes the counties referred to here as “outer-ring” counties as the “intermediate ring,” reserving the former term for more outlying areas, Sussex, Warren, Hunter-don, and Ocean. Clawson, supra at 368. The Delaware Valley Regional Planning Commission, the prinieipal Philadelphia planning group, does not describe suburban development in the Philadelphia region in terms of concentric “rings” at all, perhaps because development in that region has been more blotchy. Id. at 291.
This concededly is an oversimplified measure, see Williams & Norman, supra at 481 n. 13, but one widely used by persons in the housing construction industry. The Residential Land Supply, at 18. The $20 figure was considered conservative at the time of publication of the Department of Community Affairs study in 1972. Id.
Tlie communities are Lamberton Township (Burlington) ; Wins-low Township (Camden) ; Franklin Township (Gloucester) ; Plum-stead Township (Ocean) ; Montague Township (Sussex) ; Allamuohy Township (Warren). All are distant from the path of development and rural in character.
It should be noted that despite these restrictions a significant amount of multifamily housing has been built in the suburbs in recent years. Thus, even in Somerset County, which had no vacant land zoned for multifamily dwellings during the period between 1960 and 1970, 7,635 multifamily units were built in those 10 years. This seems to have been achieved through variances and specially procured zoning ordinance amendments. Such individually negotiated variances and amendments, however, have usually been accompanied by formal or informal restrictions limiting development to small high-rent units, which are wholly unsuited to the needs of families with low or moderate incomes. Nat’l. Comm. Against Discrimination in Housing, Jobs and Housing: Final Summary Report on the Housing Component, supra at 35-37.
Here, too, Winslow, Franklin, Plumstead, and Montague Townships are aberrant and not included.
In a few municipalities in Gloucester and Burlington Counties mobile homes are permitted in some nonresidential use areas. In a few localities scattered through the State, mobile homes are permitted as conditional uses. The Residential Land Supply, supra at 13; Williams & Norman, supra at 488-89.
Hereinafter cited as Housing Crisis in New Jersey.
As the term is used by the Regional Planning Association, which includes much of northern New Jersey.
As of 1971, 96% of all municipalities in New Jersey had zoning ordinances and 85% had subdivision controls. Sagalyn & Sternlieb, Zoning and Housing Costs 102 (1972). We need not consider here the affirmative duties of a municipality which once had but has now abandoned zoning or subdivision regulations.
While this opinion is principally directed towards municipalities, the same considerations also apply to planning at the county level when the county has chosen to exercise power to regulate land use permitted it by N. J. S. A. 40:27-1 et seq.
lt should be emphasized that citation of these cases and statutes is not intended to indicate approval of the specific zoning provisions approved therein.
Relevant considerations might include: the area included in the interdependent residential housing market; the area encompassed by significant patterns of commutation; the area served by major public services and facilities, e. g., parks, hospitals, cultural facilities, etc.; the area in which the housing problem can be solved. All of these considerations must be evaluated in terms of both present facts and projections of future development.
The following factors were considered in developing a fair share plan for the Dayton, Ohio area:
*216[T]he needed low and moderate income dwelling units were assigned to the planning units using a composite of numbers resulting from six calculation methods: (1) equal share; (2) proportionate share of the county’s households; (3) proportionate share of the county’s households making less than $10,000 annually (or less than $7,000 in the three more rural counties) ; (4) the inverse of #3; (5) a share based on the assessed valuation per pupil of the school districts covering the planning units; and (6) a share based on the relative over-crowding of the school districts involved.
* **> %
The six factors used in the calculations, however, seemed to reflect some very basic determinations: the possibility of each subarea being treated equally, the existing distribution of each county’s households and lower income households, and two indicators of the receiving school districts’ ability to accept new students. The latter two were used because the school question emerged as a critical concern whenever low and moderate income housing was mentioned for placement in a given area.
[Bertsch & Shafer “A Regional Housing Plan: The Miami Valley Regional Planning Commission Experience,” 1 Planners Noteioolc No. 1 (1971) quoted in Williams, supra § 66.36.]
In 1970 the Department of Community Affairs, in its study, Housing Crisis in New Jersey 1070, reported that 13.9% of the dwelling units in Cape Blay County were substandard, 32.8% in Cumberland, 34.7% in Salem, 16.9% in Atlantic, 19.5% in Sussex, and 23.2% in Warren. All of the counties have significant populations near or below the poverty level. Id.
Unjustifiable minimum house size requirements should, of course, be distinguished from housing code minimum space requirements which bear a real and substantial relationship to health needs. Sente v. Clifton, 66 N. J. 204, 209 (1974) (Pashman J. dissenting) ; Building the American City, supra at 215 n. 19.