LEV1029 URBAN PLANNING. We have already seen that industries or personal property representing a danger to the members of a town may be forced to close down or relocate if it is not otherwise possible to prevent such damage. We have also learned that stores and factories can be relocated out of residential areas. Both these opinions provide a halachic framework for urban planning. There is, however, a further provision regarding urban planning which, it would seem, has ramifications for what is probably the most important issue involved in contemporary environmental problems: viz., striking a balance between urban growth and the ecological needs of society. Land is one of the most important of all economic resources, and its intelligent allocation forms the basis of all healthy economies--while its misuse often dooms societies to poverty and hunger. In most developed countries, an intelligent balance between the competing needs of housing, industry, agriculture, and the amenities of health and recreation is the aim of economic policy. The Torah requires the maintenance of a green belt around each walled city, as we learn from the laws regarding the cities that were given to the Levites [Leviticus 25:34]. Each walled city had an area of 2,000 square cubits around it; the inner 1,000 were called migrash ha’ir -- the city common -- and were reserved for the animals and social amenities of the citizens. The other 1,000 (or 2,000, according to Maimonides) were reserved for their fields and vineyards. The biblical text tells us that the migrash ha’ir cannot be sold, and the Talmud explained that this means that the city common cannot be rezoned. In other words, the fields and vineyards cannot be converted into a common, nor can the common be turned into an agricultural area or, by being built upon, become part of the city. No one generation has the right to dispose of its natural resources simply as it sees fit, without handing over to future generations the same possibilities it inherited from the past.