Samuel P. Hays
University of Pittsburgh
Environmental history, arising amid public interest in environmental affairs since World War II, has taken up as wide a range of discrete subjects. In fact, the intellectual horizons of environmental history have been closely associated with the ideology of current public debate more than with a framework for understanding environmental history. In this and the following essay we seek to establish such an overall context and to examine urbanization as a significant illustration of the way in which one can work out that context.
Environmental affairs bring to history a new way of looking at the evolution of society: an expanding human pressure on a finite environment. Over the years, population, consumption and industrial technologies have created greater and greater pressure on a finite environment. Environmental history attempts to understand both the growth of those pressures and their resulting environmental effects.
Environmental history also traces changes in the way people have observed, thought about and conceived the environment around them. People have come to place new values on their natural and human environment and have developed a new interest in observing and studying their environment, making more deliberate environmental choices in their personal lives and in public policy.
The environmental agenda has given rise to a considerable number of efforts to reconstruct its history. Most of these, however, are placed not within the context of historical questions such as patterns of long-run change in human values and institutions, but of attempts to attach historical meaning to current policy choices. Many, perhaps most, write environmental history primarily to sustain arguments that seek to redirect the course of environmental thought and policy. This gives environmental history a markedly ahistorical bent.
Here I attempt a more distinctive format for environmental history by focusing on two large questions. One is to look at the evolution of human society through the context of changing environmental circumstances and the other the equally key question of the changing ways in which people have thought about, valued and acted in relationship to their environment, that is, the problem of environmental engagement. The first consists of the ways historians can apply an environmental perspective to the description and analysis of evolving human circumstance with the primary theme of the expanding human pressures on the finite environment and the second consists of a more distinctive focus on human perceptions of their environment and their response to that perception.
For both of these historical problems one of the most promising conceptual vehicles is the city. The city is the focal point of increasing human congestion with its accompanying changes in urban environmental circumstance and its sharp contrast with the environmental circumstance of the seemingly less environmentally pressed countryside. Cities generate increasing loads on the wider environment which, in turn, establishes the tension in larger environmental circumstance.
The city is also the starting point for new attitudes about the wider environment. Organized environmental action as well as favorable environmental opinion is stronger in the city than in the countryside. New views about the value of land, air and water of the world outside the city as environments rather than as commodities arise from the city. Resulting patterns of political controversy are organized primarily in urban-rural terms.
We first look at urbanization, therefore, in the evolution of environmental circumstance and then as the source of the new world of environmental engagement.
The City’s Role in Changing Environmental Circumstance
Urbanization plays three roles in changing environmental circumstance. The first is the evolution of the environment internal to the city; second is the way in which the city reaches out to influence the wider countryside; and third is the effect of this outreach on environmental transformation of that wider world. We take up each of these in turn.
The environment internal to the city went through several stages of historical development in the 19th and 20th centuries. These stages should not be thought of as sequential, but cumulative, as each new stage emerged out of a previous one that continued, into a growing combination of newer and older environmental conditions as some changes became more extensive and others less so. We mark these changes roughly, more for convenience than for preciseness, with the first and second halves of each of the two centuries.
I. The human/environmental setting of the emerging towns and cities of the first half of the 19th century (1800-1850) involved the transfer of social practices long-established in the countryside to the new places of more concentrated population. Newly arrived migrants to the city sought to continue familiar rural ways of life and found that practices quite acceptable in more spacious rural areas affected people quite differently in this more congested environment and were looked upon with revulsion and resistance. The new environmental circumstances gave rise to many town and city ordinances to restrict customary practices.
The most pervasive of these involved the role of farm animals--cows, horses, pigs and chickens--in the towns. At first farm animals were allowed to roam the street; their smell, their waste and the damage they did to property interfered with the lives of others. Initially they were considered to be unpleasant nuisances but soon were thought of as a health problem, giving rise to some of the first urban-inspired public health ordinances.
Several features of urban life are seemingly minor but instructive elements of this transition. One was the burial of the dead. In rural areas some dead were buried in formally organized church cemeteries but even more in plots on family lands. In the city places for burial were not as freely available and often the dead were not cared for and became a public health concern. Ordinances required that church sextons report deaths, but in the last half of the 19th century, they required that deaths be reported by a coroner. Another was the gradual removal of horse racing from urban streets to the edge of cities and then to specialized tracks removed from daily human activity as they interfered with urban transport. This transfer reflected the shift of town and city street-based recreation to areas separated from urban congestion.
II. A second phase (1850-1900) in the internal environmental history of the city arose as increasing urban density created undesired environmental circumstance. One might describe this as the emergence of the contradictions of the city as a place to work with the city as a place to live, contradictions which continue to the present day. Some arose from the cumulating presence of urban-generated waste that gave rise to a shift from the outhouse to sewage ditches and underground lines to divert waste to nearby rivers and away from the city. Others arose from the development of industrial districts, for example, for the petroleum industry, that gave rise to concentrated forms of residential degradation. Still others arose from the increasing intensity of transportation that involved the loss of city streets as residentially-related open space. New forms of communication such as telephones and outdoor advertising or new forms of energy such as electricity brought environmental blight along with material benefits. And still others involved attempts to control disease and improve health with safer drinking water and removal of solid waste from yards and streets. And as an overall problem the increasing intensity of development preempted open space and gave rise to the city’s ever-increasing loss of natural features.
These changes brought sharply to the city the tension between efforts to enhance benefits that came from higher density living and the accompanying liabilities in quality of life. Here was conflict between the city as a source of production and work on the one hand and the city as a place to live on the other. Greater population density gave rise to demands for new services to benefit the entire community;. But they also gave rise to adverse consequences that had to be endured or ameliorated in some fashion if they were to be avoided. Urban growth and development involved both environmental improvement and environmental degradation, a tension that moved along steadily in succeeding stages of urban history.
Within the city the pressures toward more intensive development of urban land and hence to reduce open space involved a three-fold set of relationships. More intensive and congested urban life led to an increasing demand for urban public services; municipal governments sought to raise revenue to pay for public services not by raising tax rates, to which there was massive objection, but by raising assessed valuations and, in turn, the least painful way of raising assessed valuations was through more intensive building which raised property values. At many times in future years those who sought to improve the environmental quality of the city found themselves confronted with this deeply embedded triangle of factors, a triangle that arose quite early in the history of the development of public works as public services.
III. A third phase in the internal environmental history of the city, especially dramatic in the first half of the 20th century (1900-1950), was generated by the attempt of many urban residents to carve out new homes and residential areas in the city that would provide more pleasant living. In earlier residential patterns, factory workers lived near their work and artisans lived in the upper floors of their shops. Increasing numbers of people became unhappy with the unpleasant impact of production on the quality of residential life; they made choices to live in places separate from work and in doing so to emphasize the desired features of new residential areas.
This tendency was facilitated by the courts which continually heard nuisance cases against factories brought by their neighbors, but for the most part dismissed the complaints. Many plaintiffs, so the courts argued, bought their property knowing about the noise, air and water pollution or the congestion they now faced; hence they had no case. Others who as property owners faced new factories that changed the quality of their land also had no case because the benefits from factory production outweighed the interests of residential owners. The first involved the interests of the public as a whole and second the interests of only a few.
The desire for residential quality of life was rather widespread but the ability to fulfill it depended on sufficient income and hence was affordable to most residents only as their income increased. Those at the lower end of the occupational scale--the industrial workers--took modest but important steps from living in housing around mills to moving upward in job skill and income, and thus seeking improved housing. Often they moved to new residences up the hillsides from the river-valley flats of mill housing; here they could have a more “livable” environment both within the house--enjoying a “living room” for example--and also a more livable environment outside the house away from the unpleasant environment of the mills.
A more visible residential pattern emerged on the part of white-collar workers, a group steadily growing in numbers over the years and by 1900 constituting a group with distinctive residential objectives with marked environmental features. Earlier these workers lived above the artisan shops of the central city while unskilled laborers lived in the back alleys. But as incomes rose these more affluent workers were attracted to new areas of the city where they could enjoy not only larger houses, but more spacious communities with front and back yards, trees along the edge of their property, vegetable and flower gardens, paved streets, piped water and sewage lines, and life at some distance from the congestion and unpleasant environmental circumstances of older areas of the city.
This drive to carve out more environmentally attractive areas in the city led to efforts to protect those areas from what were considered to be more environmentally undesirable influences. The private market for urban land led to frequent changes in ownership and the continual potential that land adjacent to residences would become commercial or industrial with its accompanying detrimental environmental effects on residential property. As a homeowner how could one control this potential danger? In some cases residential real estate developers placed in deeds requirements that residences be set back a certain distance from the street. In other cases areas of residential property were developed with collective deed restrictions and in some cases, though few, limited access. But the most widely developed approach was zoning in which municipal zoning commissions established zones to which industrial, commercial or residential development each would be confined.
IV. In the years after World War II (1950-2000) these long-evolving tendencies now came together in a more unified effort to define urban environmental conditions and to improve them as a collective set of urban circumstances called environmental. One could describe this as a relatively coherent effort to define the city as a place to live as well as a place to work. The change could be observed especially through the work of planning agencies. In the early years of planning the task was thought of largely as providing services for expansion of long-established industrial enterprise. After World War II, however, urban planning came to encompass a wide range of “quality of life” considerations such as parks, playgrounds, open spaces, hiking and biking trails, museums and recreational facilities, commercial areas with more greenery, reduction of air and water pollution and more spacious central city areas.
A wide range of activities were set in motion to carry out these objectives. Sewage-treatment works supplanted earlier established waste-water pipes and channels with discharge of raw sewage into streams. Air pollution was reduced through a series of efforts such as decisions by homeowners to substitute less polluting natural gas for more polluting coal. Cities advocated purchases of public lands by both counties and states for parks and natural areas. There were changes in urban land use, such as urban redevelopment; the decline in river- front, river-traffic related activities; and the decision to end military uses of military bases in order to carve out more natural environment areas accessible to urban residents.
To these new expressions of urban environmental objectives there was often much resistance. As was endemic in the history of cities, the environmental quality of the city as a place to live, still faced vigorous competition from pressures to define the city more as a place to work. Urban concerns for more jobs and more income continued to outweigh urban concerns for quality of life. Few urban governments sought to give environmental affairs a central place in their policies or planning for the future. While states often, for example, brought these issues together into a focused administration, few cities did so. And “futuristic” thinking was dominated by the desire to determine how urban population and income could grow rather than by how environmental quality of life could grow.
The Environmental Reach of the Urbanizing Society
Cities were one of the major expansive forces in modern 19th and 20th century America. Their history is the story of the way in which large numbers of urban people with their rising levels of consumption imposed themselves on and transformed the countryside and region. Both the imposition and the transformation are essential elements of environmental history. But this story requires a major change in the vision of urban historians who have looked upon cities as isolated from rural history and to whom urban-rural relations rarely occur save as peripheral vision. An environmental perspective requires a combined urban-rural context. Environmental history, in fact, provides an opportunity for urban historians to broaden their vision and to focus more sharply on the countryside, not as a dominant force in the evolution of society but as an essential part of an integrated urban-rural context.
A. Urban Penetration into the Countryside
Urban penetration into the countryside took place in stages as one type of outreach arose after another to blend in a cumulative development over the years. At one time the resulting urban-rural relationships were limited in scope and direction; with time the impact of cities on the countryside became more extensive and intensive. The environmental reach of the urbanizing society penetrated larger regions, nations as a whole, and the wider common environment of oceans and the atmosphere.
In its earliest outward reach growing urban areas sought the products of the earth not available within their boundaries but present in the surrounding rural areas. Some were used directly for fuel, others as raw materials for more highly processed consumer products, and much was used for food. These uses were, of course, integral parts of the rural society out of which urbanization sprang, but the demands on these resources became ever-more intensive as the number of urban people and their consumer demands grew.
Forest history provides one of the more obvious and dramatic cases. Timber harvest for urban construction is one of the major themes in the history of both urbanization and forestry. Use of the vast pine forests of the Upper Lakes states for reconstructing Chicago after the Great Fire is one of the better-known recorded incidents in this urban-rural relationship. But many a city went through a similar experience. Demand for construction lumber was so great that the vast “virgin” forests were soon depleted and the industry moved on from region to region until the forest resources of the entire nation were extracted by urban-based demands.
The most widespread urban use of the countryside, however, was for food. When people moved to cities they purchased some food, such as grain, from the markets, but also often sought to grow perishable food, such as fruit and vegetables. With time, however, and new forms of food preservation, these also came to be supplied by rural growers. Urban demands on agricultural production took a new turn in the last half of the 20th century as a host of new “farm” products began to be a major part of the consumer market: food specialties such as herbs, horticultural products such as urban flower gardening. Taken together, these more intensive urban demands for the products of farm and field constituted an increasing “load” on the limited land resources of the world beyond the city.
A distinctive phase of the urban demands on the countryside came with urban needs for water. Early towns and cities drew upon sources from rivers and wells. But as urban use increased cities reached out to obtain supplies farther away. Many a growing city acquired land in watersheds above them to protect their supplies. This was especially the case in the earliest urbanization of New England and the middle Atlantic states. Mid-American cities located on rivers, such as Pittsburgh, Cincinnati or St. Louis had nearby river supplies that were relatively accessible. Other cities, such as Denver and Los Angeles, had to reach out to more distant supplies; here urban and rural people competed vigorously for the limited supplies.
The history of wildlife, in earlier years the history of sport fishing and hunting, played an equally significant role in the impact of cities on the countryside. Immigrants from Europe had been excluded from hunting and fishing on property of the nobility and royalty, but in America fish and game were public resources widely accessible. As urban people increased their fishing and hunting activity, they increased pressure on a limited resource and demanded that state agencies increase the supply by artificial propagation.
Interest in wildlife for its nongame and aesthetic appeal was almost entirely a product of the cities and often led to a revulsion against hunting. Some demanded wildlife products for their ornamental value such as elk teeth prized by the fraternal society, the Elks, or bird feathers for women’s hats, or furs for women’s coats. In the 20th century, urban interest in wildlife took quite a different turn with the focus on wildlife not for consumption or decoration but on its appreciation in the wild. Urban people came to be interested in forest areas as habitat for wildlife and many an urban-based organization advocated the acquisition and management of public land as habitat for a wide range of species. The term biodiversity arose to describe this broader range of wildlife concerns that arose from the new interest of urban people.
B. Urban Use of the Countryside for Waste Disposal
Urban people and industries produced much waste that cities did not feel they could absorb within their own boundaries. Hence they sought to use the countryside for its disposal. In some cases industries that produced particularly offensive waste were under pressure to relocate outside the cities. But most urban waste was disposed of by using the countryside as a place “out there” for waste disposal. At first that “out there” was relatively close by, but as time went on, the amount of waste increased and residential suburbs moved outward, and, in turn, the place of disposal was further and further away.
Nearby rivers were one of the first places used for urban waste disposal. Water-borne wastes were dumped into drainage ditches, a process that increased dramatically with indoor plumbing. At first confined to upper income groups, indoor plumbing became extended to middle and lower income homes in the 20th century. At the same time underground sewers replaced open drainage ditches with sewer outfalls into the nearby rivers. Thus, the cities found it readily possible to use a public resource, a river, to remove waste from within its borders. At first there was little resistance from people “out there” who might find their interests in cleaner rivers to be infringed. Industries also used this public resource for their own benefit, thereby expanding the waste loads in rivers. In some cases industries argued that the highest and best use of rivers was for industrial waste disposal.
The emission and transport of airborne waste in the form of air pollution went through a similar history. Earlier one thought of air pollution as local, falling out close to the sources from which it originated. But later it was discovered that air emissions traveled long distances to be deposited hundreds and even thousands of miles away. The countryside where the airborne urban waste came to rest was extensive in its geographical scope and hence expanded the environmental reach of the city to wide-ranging areas in the region, the nation and beyond.
A new form of air-borne discharge came from the widespread use of toxic chemicals, created expressly to create materials not subject to rapid biological decay. Because they were persistent they penetrated the atmosphere far more widely than did other chemicals and were found in the environment throughout the world. In the first well-known discovery of this process, DDT was found in the fat of penguins in Antarctica. Tracking the pathways of toxic chemicals was often extremely complex, as they went through a sequence of deposition and volatilization that required far more detailed and continuous measurement. This far-reaching penetration of persistent chemicals even came to adversely affect the conduct of scientific research; dioxin in human fat, for example, was so widely distributed among human populations throughout the earth that people with no or little dioxin could not be found with which to contrast those with higher levels.
The countryside, near and far from cities, became an ultimate “sink” for chemicals generated by urban society. Treated wastewater left a residue of solids, such as sewage sludge which gave rise to urban demand for rural land disposal. Emissions of sulfur dioxide were reduced through “scrubbers” that turned air-borne waste into a solid that was disposed of in landfills. For commercial and household solid waste, the rural-sited landfill was the customary disposal method and the same was the case for toxic wastes from industry.
C. Occupation of the Countryside for Recreation and Leisure
Urban people also directly occupied the countryside and thereby extended the environmental reach of the city. Early in the development of urban areas city people sought out the countryside for diversion, relaxation and health. If the environmental quality of cities had its drawbacks the more natural countryside had its benefits. At first this opportunity was available only to the more affluent, but over the years the urban-based use of the countryside for recreation, relaxation, health and appreciation of nature, grew in its range and intensity. This long-range process brought the city into a new and dominating influence in rural areas that linked city and country ever more tightly.
Very early in the history of American urbanization resorts grew up to cater to a small group of affluent urbanites. Warm springs for health purposes arose in the pattern of European spas. Doctors often advised patients to leave the city in the summer to improve their health through breathing cleaner air. At the same time wealthy urbanites not only established their own estates in the countryside but organized private hunting clubs, such as in the Adirondacks.
In the early 20th century this urban-based and urban-inspired use of the countryside went through a veritable revolution as a result of the automobile. As the automobile grew from a plaything of the wealthy to providing greater mobility for middle-income Americans it generated a vast increase in fishing and hunting and outdoor recreation in the countryside. Federal and state parks and recreation areas began to take shape in the 1920s to give rise to a massive increase in outdoor recreation in the 1930s. Slowed during World War II, outdoor recreation took off once again after the War and gave rise to an expansion of federal and state outdoor recreation programs, with new twists such as hiking trails, protected wild and scenic rivers and wilderness areas.
In later years urban interest in the countryside came to include the ecological context of the forest, well beyond its use for wood products, to its role as a habitat for wildlife. This was influenced heavily by the urban- based interest in “appreciative” uses of wildlife, reflected in numerous wildlife television programs and the growth of environmental education. Nongame wildlife policies arose in almost every state, leading to the purchase of natural areas to be managed for ecological purposes with “biodiversity” as the objective.
Outdoor recreation came to be closely allied with tourism for which the largest number of participants came from urban areas. But it also evolved into more permanent occupation of the countryside through ownership of property there used at first for week-end recreation and relaxation and later for permanent residence. This urban-inspired demand for rural property fragmented forest lands into smaller properties so that most forest land in the east was owned by “non-industrial, private forest owners” rather than industrial forest corporations. These new owners valued their property far more for its natural environmental quality than as a source of wood production.
Interest in less developed land in the countryside led to the growth of land conservancies, a new form of protecting land from development. These were private efforts to acquire land, manage it for its natural values, prohibit or greatly restrict development, and stress low-impact outdoor recreation, nature study and environmental education. They often also served as centers for environmental monitoring and a base for ecological research. By the end of the 20th century over 1000 land conservancies had been established, most of which drew support from people interested in a particular place who sought to ensure that natural values would be “saved” for later generations.
Transformation in the Countryside
Urban penetration into the larger world around the cities transformed it in many ways. The scope and intensity of the impact increased steadily. Some changes were geological, such as soil disturbance, through mining, erosion through logging and farming or wetland drainage. Some were biological as wildlife habitat was replaced with intensive agriculture, or transportation and communication corridors fractured wildlife habitat and exotic plants displaced native ones. Others involved the addition of chemicals emitted from urban-based technologies, such as fuel burning, to the natural chemical cycles that tied together much of the larger natural world. And still other changes the simple process of declining open space as humans increasingly preempted that space for more permanent occupation and development.
Environmental historians have examined bits and pieces of this but usually only within the limited perspective of the urban dweller and hence somewhat oblivious to the effects of the urban-based pressures on the wider world. Here we look at it from the viewpoint of changes in the land, air and water resources themselves. Economic history usually emphasizes penetration into the countryside in terms of the way in which it met the objectives of the developers who promoted it. Environmental historians seek to bring into this one-sided perspective the environmental transformations on their own terms.
How, in the latter part of the 20th century, does one reconstruct geological and biological changes over the past two centuries? Intrigued with the task, many researches have tried to ferret out evidence to mark long-run environmental change. Dendrologists have long looked at tree rings to reconstruct forest history. Geologists have explored the Greenland ice cap to examine the residues of metals distributed through the atmosphere. Biologists have examined diatoms in lake sediments to examine early patterns of agricultural and forest activity and paleobiologists have examined charcoal remains to determine patterns of forest use and settlement among Native American peoples. A variety of researchers have compared levels of lead in people living in industrial cities from those in areas untouched by lead emissions or in the bones of mummies from earlier times. Most such studies, however, have been carried out by natural scientists somewhat removed from the “mainstream” of environmental history.
Land and Water. Extraction of minerals left many changes in the countryside, ranging from the open pits left from mining, the piles of residue coal waste, acid water that transformed the chemistry and biology of streams, or the accumulation of mining waste in sediments of lakes, rivers and reservoirs. As people sought places to live in a more natural and pleasant environment, they found these residues from both past and present mining to be eyesores which they sought to eliminate. And as the scale of water pollution from mining increased those who enjoyed fishing found it threatened their recreational activity.
Forest transformation was far more extensive, involving massive biological changes over vast areas of land. The older forest existing at the time of European settlement was modified drastically. Native Americans had long cleared limited, local parts of forests through fires, but Europeans cleared it more fully and more permanently for agriculture. Forest historians have emphasized both the loss of trees through massive harvest and the regeneration which created new forests. Thus the trees cut over in New England were succeeded by second- growth. But far more extensive changes took place in the forest ecosystem as a whole, well beyond the trees alone- -plants of all kinds, invertebrates as well as vertebrates, lichens and butterflies, wildflowers and shrubs, frogs, salamanders and other amphibians. Recovery of the forest ecosystem was slow; some species became extinct.
Land development for agriculture was the most massive transformation in the countryside. In same cases, such as New England, farming the hill land gave way to farming the more productive soils in the West and led many owners to abandon their land. The same pattern was repeated in the upper Great Lakes states; the hope of converting cutter pine lands to agriculture did not materialize because it was found that the soils were far too sandy. But on vast tracts of land, farming replaced forest and native wildlife; farming became increasingly intensive and a source of pollution itself.
Rivers also changed. Where water was abundant and rivers flowed through terrain of only small elevations they were used for transportation, a use extended by canals. In other cases they became a water supply for industry or domestic use which led to construction of reservoirs which modified their natural flow and reduced fish populations on natural habitat. In areas of limited rainfall such as the West flow was diverted for agriculture and then stored in reservoirs which constituted even more massive disturbances of natural river regimes. In many cases rivers were used as the most convenient method of disposing of waste and over the years this practice went on relatively unabated. For many years these changes in rivers met with little opposition and what did occur usually only from those immediately affected. Not until after World War II did public opinion change as many people began to emphasize the value of cleaner and “free flowing” rivers. As people penetrated the countryside to remove its raw materials, to change forest land to farmland, or to extract water from rivers, they found that some areas were not attractive and bypassed them. In some cases they were too mountainous in which to build transportation lines to make them more accessible; in other cases the soils were too thin, taking on the characteristic of what were called “barrens.” Some rivers in the higher elevations were too rocky for transport of any kind, neither by boat nor for floating logs. Some wetlands were too deep and extensive to drain for agriculture. Hence the process of human penetration was selective; the intensity of occupation varied from place to place. From the point of view of an economic history that emphasizes the extraction of resources these were merely “wastelands.” But from the point of view of environmental history these were “lands that nobody wanted,” left for future generations to prize as lands of great value amid the massive land and water development of the 20th century.
The Web of Chemical Cycles. Changes in land and water were the most obvious environmental changes; they could readily be seen. Less visible, more subtle and perhaps more profound changes involved airborne chemicals that traveled long distances, even to other continents and around the globe. These pollutants were deposited far and wide to accumulate in the environment and affect plants, animals and soils. Dramatic pollution episodes were fodder for media coverage, the more subtle changes were not.
Chemical transport through air and water brought into environmental and ecological science the notion of chemical cycles, in which chemicals traveled long distances between their origin and their deposition, some of which were transformed during transport. In the normal course of natural cycles the environment had absorbed these chemicals with little environmental disturbance. But as atmospheric chemical loads increased from human activities they constituted increasing loads that were not readily absorbed. Hence one spoke of the cycles as being overloaded beyond the absorptive capacity of the underlying geological and biological environment. At the same time the idea of “critical load” arose, such loads were sufficiently high to endanger the underlying ecosystem and scientists began to work out the level of deposition that would be tolerated in contrast with that which could not.
This was especially the case with “persistent” or “nonbiodegradable” toxic chemicals which moved through the environment to accumulate in air, water and land and the associated plants and animals. While many chemicals degraded rapidly as they were transported through the air, others, especially metals and synthetic chemicals were far more persistent. As environmental science persistently brought more of the environment and how it worked into the realm of knowledge, the pervasiveness of toxic chemicals became a growing part of the perceived human experience. And this included changes in biological resources beyond the cities in the countryside and the wildlands.
Concentrations of these chemicals were such that they were not readily noticeable. They required measurement at low levels of concentration in order to be tracked and understood. This was one of the major tasks of environmental science. Some studies tracked metals such as lead in areas downwind from their sources, such as from the Pittsburgh steel industry to “sinks” some 50 miles east of the city and even at longer distances to the Greenland ice caps. Others measured accumulations in lakes or in wildlife which either revealed changes in the chemistry and biological life of lakes, or disruptive toxic chemicals in wildlife that through external observation seemed to be healthy. Such studies gave rise to the view that chemical deposits were wide-ranging and all pervasive, that waste from modern urbanized society had given rise to a comprehensive, global process of “biogeochemical” accumulation.
Settlement in the Countryside. Urban-inspired human settlement in the countryside generated its own forms of environmental degradation, through its impact on less highly developed areas. The countryside invited an increasing number of people who came to enjoy the higher quality environments on week-ends and during vacations and then to live there. Some took up occupations more characteristic of small towns and nearby rural areas; others were retirees whose main focus was not occupation but quality of life; still others held occupations in the “footloose” industries afforded by modern communications technologies so that they could live and work in areas of considerable natural quality and carry on far-flung business ventures. All this was observed even in the census of 1930 as a “rural, non-farm population.” This new rural category grew over the years and its environmental effect was profound.
One of its most striking effects was to transform large forest land ownerships into those of much smaller scale. By the 1960’s a considerable transfer of forest ownership had occurred from rural farm and commercial holdings to woodlots owned primarily by people from urban areas. Urban-based income was now used to purchase woodlands for recreation or permanent homes. A massive turnabout in rural land values resulted. Prior to World War II rural land values had continued to decline as farming was less and less profitable, some lands were abandoned and traditional uses declined. But after World War II rural land values rose steadily. Real-estate ads reflected the process, as sellers in rural areas advertised in urban papers and described their lands for sale in highly positive environmental terms--quiet areas, cleaner air, abundant wildlife, by a sparkling stream, near a state park or forest.
These new settlements greatly fractured forest lands into fragments and highlighted a condition of forest habitat known as “fragmentation.” Large forest areas that constituted habitat for plants and animals requiring a distinctive type of “intact” forest declined while the number and extent of small woodlots, of 100 acres or so, increased. Plants and animals living in fragmented areas were quite different from those in larger forest areas. Hence while some neotropical songbirds lived in the larger habitats others lived in the smaller ones. The transformation in size of holding had a profound effect on the populations of plants and animals, producing conditions favorable to those that could co-exist with humans in settled and fragmented areas and unfavorable to those that required less disturbed areas.
To track these changes in the wider environment beyond the areas of high urban density but directly a result of the impact of cities on the countryside is one of the major challenges of environmental history. A convenient device for doing so is to compare areas of varied levels of urbanization, suburban areas close to cities, countryside areas further away and wildland areas, the least disturbed by humans. These impacts can be thought of as the comparative environmental effects of cities on the wider environment as urban-based human demands escalate amid the surrounding finite air, land and water of the region, the nation, and the wider globe.