This is a copy of an article found under below link with minor comments from my side. The article underlines my thinking on global networks of cities. https://irows.ucr.edu/papers/irows28/irows28.htm
Systems of cities represent human interaction networks and their connections with the built and natural environments. Logically, the study of city systems is a subcategory of the more general topic of settlement systems. Once humans began living in fairly permanent hamlets and villages it became possible to study the interactions of these settlements with one another. Settlements are rarely ever intelligible without knowing their relations with the rural and nomadic populations that interact with them. Archaeologists, ethnographers and, of course, geographers, map the ways in which human habitations are spread across space, and this is a fundamental window on the lives of the people in all social systems.
The spatial aspect of population density is one of the most fundamental variables for understanding the constraints and possibilities of human social organization. The “settlement size distribution” – the relative population sizes of the settlements within a region– is an important and easily ascertained aspect of all sedentary social systems. And the functional differences among settlements are a basic feature of the division of labor that links households and communities with larger polities and interpolity systems. The emergence of social hierarchies is often related to size hierarchies of settlements. And the building of monumental architecture in large settlements has been closely associated with the emergence of more hierarchical social structures – complex chiefdoms and early states.
The role of city systems in the reproduction and transformation of human social institutions has been altered by the emergence and predominance of capitalist accumulation, and by the control over mortality which has emerged within the same historical-economic context. By their very nature urban populations require a “surplus” of agricultural production in order to survive because urban places are inherently non-agricultural. Furthermore, prior to the control over mortality, the crowding of people into urban environments almost invariably increased the spread of disease and raised the level of mortality compared to rural places, and so the rate of natural increase in most urban places for most of human history was negative.
For this reason, urban places needed constantly to recruit from the countryside in order to sustain population size. Thus, whereas most of the important cities of agrarian tributary states were centers of control and coordination for the extraction of resources and labor from vast empires by means of institutionalized coercion, the most important cities in the modern world have increasingly supplemented the coordination of force with the manipulations of money and the production of commodities. Obviously military force is still an important element of power in the modern world-system, but the uses of military power have been fundamentally altered by the predominance of capitalist accumulation. Furthermore, recruitment of labor has been fundamentally turned on its head by the dramatic decline in mortality taking place over the past centuries, which has (a) lowered death rates in cities more than in rural areas, producing positive rates of natural increase, and (b) lowered death rates in rural areas to levels well below fertility, producing high rates of rural population growth, leading to a redundancy of the rural population which then produces a steady flow of migrants to the cities in search of jobs (Davis 1972; 1973; Weeks 2002).
Power and Size: Cities and Empires
What is the relationship between the size of settlements and power in intergroup relations? Under what circumstances does a society with greater population density have power over adjacent societies with lower population density, and when might this relationship not hold? Population density is often assumed to be a sensible proxy for relative societal power. Indeed, Chase-Dunn and Hall employ high relative population density as a major indicator of core status within a world-system (Chase-Dunn and Hall 1997). But Chase-Dunn and Hall are careful to distinguish between “core/periphery differentiation” and “core/periphery hierarchy.” Only the latter constitutes actively employed intersocietal domination or exploitation, and Chase-Dunn and Hall warn against inferring power directly from differences in population density.
In many world-systems military superiority is the key dimension of intersocietal relations. Military superiority is generally a function of population density and the proximity of a large and coordinated group of combatants to contested regions. The winner of a confrontation is that group that can bring the larger number of combatants together quickly. This general demographic basis of military power is modified to some extent by military technology, including transportation technologies. Factors such as better weapons, better training in the arts of war, faster horses, better boats, greater solidarity among soldiers and their leaders, as well as advantageous terrain, can alter the simple correlation between population size and power (Turchin 2005).
George Modelski (2003) has recently published a long-term study of city sizes in world history. It is a formulation and testing of a theoretical model of human social evolution that focuses on the growth of world cities and it is also presents results of a huge empirical effort to expand our knowledge of the population sizes of the largest settlements on Earth since the Bronze Age. Modelski utilizes the data on city growth to evaluate his theory of social evolution. The growth of cities is a useful indicator of world system evolution because the ability of a society to produce and maintain a large settlement is a major accomplishment. We can trace the emergence of social complexity by knowing where the largest human settlements are at any point in time. Beginning with Uruk, the first “world city’ five thousand years ago, Modelski traces the emergence and spread of large cities from Mesopotamia and Egypt to East Asia, South Asia, Europe and the Americas.
Ironically, Modelski’s (2003) important study of the growth of world cities completely ignores the growth of states and empires, though Modelski is himself an astute scholar of international relations and geopolitical power. Modelski contends that cities are the most important driving force of world system evolution and that we may conveniently ignore states and empires. The relationship between political power and settlements itself evolved over the millennia, so that analysis of the relationship between size and power is necessary in order to understand what happened.
Modelski’s evolutionary approach focuses on a single world system that begins with the first cities and states in Mesopotamia5000 years ago, and spreads out to become global. In focusing on this single system he ignores the differences between regions and civilizations that are of interest to other world historians, but his focus on world cities across large expanses of time allows him to see patterns that other analysts miss.
Regarding the city population data, Modelski has extended and improved the work of that most eminent coder of city sizes, Tertius Chandler (1987). For students of urban and world history this work is of immeasurable value. Modelski has labored hard to produce the best comprehensive compilation of estimates of city population sizes now available.
Modelski’s careful improvement upon earlier efforts to estimate the population sizes of ancient cities is a huge step forward. He uses estimates of the built-up area of a city and a population density factor (see p. 11 and Note 5 on p. 17) to estimate the population sizes. He adds considerable depth, especially to the coverage of the Bronze Age.
In the “ancient era” (-3000 to –1000) world cities are defined as those that reach a population size of 10,000 or more. In the following “classical era” (-1000 to 1000) cities must be at least 100,000 in population size to count as world cities. And in the modern era (since 1000) the cut-off point is one million. Modelski observes a phenomenon, also noticed by Roland Fletcher (1995), that a few cities are the first to reach a whole new scale, and then a size ceiling is encountered during which cities in other regions catch up to the new scale. The current maximum seems to be around twenty millions and the phenomenon of catching up is now occurring. Some of the world’s largest cities are now in developing countries such as Mexico, Brazil, China and India.
Modelski’s study of the phases of urbanism is convincing regarding the contention that urbanization has been neither random nor linear. Instead it has followed a recurring pattern of rapid growth followed by slow growth or decline. A phase of fast growth concentrated in one or a few regions is followed by slower growth and the diffusion of large cities to other areas. Rapid and concentrated growth is followed by leveling off and dispersal due to “countervailing forces.” These countervailing forces emerge from what Modelski terms the “Center-Hinterland” divide of a regional world system. The first growth phase emerges in a center that eventually encounters limits to growth from resource exhaustion, environmental stress and “failures of knowledge.” The leveling process occurs as these limits are reached, weakening the old center. Incursions from the hinterland increase, taking advantage of the center’s weakness. This allows the semi-hinterland, a region adjacent to the old center with smaller cities, to catch up to the urban scale of the old center.
Modelski also compares his phases of urban growth with existing estimates of overall population size and growth. He finds that the overall population growth phases correspond in time with the urban expansions of the three eras. This study leads to what Modelski calls a “manifest case of evolution.” The three phases of urbanization correspond to periods of world system evolution: cultural, social and political. The ancient cultural phase saw the creation of a learning structure based on cities, writing and calendars, resulting in a platform for sustained and intensified human interaction on a large scale. The classical social phase brought about a more extensive, inclusive and integrated system. Expanding during Karl Jasper’s “ Axial Age,” the cities of the classical period can be grouped according to the world religions that dominated social structures during that era. The modern political phase poses choices regarding an evolutionarily stable structure of world organization. Modelski predicts that the future fourth phase will be an economic one that will see a “stabilization and consolidation of the economic and material basis” of world society.
While this learning model of human social evolution may seem a bit too functionalist or Whigish to some, it has original theoretical elements, such as the center-hinterland dynamic, that have been absent from most earlier evolutionary models. This, plus its monumental empirical contribution, makes this an extremely valuable step forward toward our comprehension of the human experiment with complexity.
Semiperipheral Development and Cities
The most important general exception (in comparative evolutionary perspective) to the size/power relationship discussed above is the phenomenon of semiperipheral development. The pattern of uneven development by which formerly more complex societies lose their place to “less developed” societies takes several forms depending on the institutional terrain on which intersocietal competition is occurring. Less relatively dense semiperipheral marcher chiefdoms conquer older core chiefdoms to create larger chiefly polities (Kirch 1984). Likewise, semiperipheral marcher states, usually recently settled peripheral peoples on the edge of an old region of core states, frequently are the agents of a new core-wide empire based on conquest (Mann 1986; Turchin 2003).
Another exception is the phenomenon of semiperipheral capitalist city-states – states in the interstices between tributary empires that specialized in long-distance trade and commodity production. Though these were rarely the largest cities within the world-systems dominated by tributary empires, they played a transformational role in the expansion of production for exchange and commodification in the ancient and classical systems. And less dense semiperipheral Europe was the locus of a virile form of capitalism that condensed in a region that was home to a large number of unusually proximate semiperipheral capitalist city-states. This development, and the military technology that emerged in the competitive and capitalist European interstate system, made it possible for less dense Europe to erect a global hegemony over the more densely populated older core regions of Afroeurasia (Chase-Dunn and Hall 1997). The more recent hegemonic ascent of formerly semiperipheral national states such as the Netherlands,England and the United States are further examples of the phenomenon of semiperipheral development.
The phenomenon of semiperipheral development does not totally undermine the proposition that societal power and demographic size are likely to be correlated. What it implies is that this correlation can be overcome by other factors, and that these processes are not entirely random. Denser core societies are regularly overcome or out-competed by less dense semiperipheral societies, but it does not follow that all semiperipheral or peripheral regions have such an advantage. On the contrary, in most world-systems most low-density societies are subjected to the power of more dense societies. Semiperipheral development is a rather important exception to this general rule.
Why should a city system have a steeper size distribution when there is a greater concentration of power? The simple answer is that large settlements, and especially large cities, require greater concentrations of resources to support their large populations. This is why population size has itself been suggested as an indicator of power ( e.g. Taagepera, 1978a: 111). But these resources may be obtainable locally and the settlement size hierarchy may simply correspond to the distribution of ecologically determined resources. People cluster near oases in a desert environment. In such a case it is not the political or economic power of the central settlement over surrounding areas that produces a centralized settlement system, but rather the geographical distribution of necessary or desirable resources. In many systems, however, we have reason to believe that relations of power, domination and exploitation do affect the distribution of human populations in space. Many large cities are as large as they are because they are able to draw upon far-flung regions for food and raw materials. If a city is able to use political/military power or economic power to acquire resources from surrounding cities, it will be able to support a larger population than the dominated cities can, and this will produce a hierarchical city size distribution.
Of course the effect can also go the other way. Some cities can dominate others because they have larger populations, as discussed above. Great population size makes possible the assembly of large armies or navies, and this may be an important factor creating or reinforcing steep city size distributions.
The relationship between power and settlement systems is contingent on technology as well as political and economic institutions. Thus the relationship between urban growth and decline sequences and the growth/decline sequences of empires varies across different systems or in the same regional system over time as new institutional developments emerge. We know that the development of new techniques of power, as well the integration of larger and larger regions into systems of interacting production and trade, facilitate the emergence of larger and larger polities as well as larger and larger cities. Thus, there is a secular trend at the global level and within regions between city sizes and polity sizes over the past six millennia (Chase-Dunn, Anderson and Turchin 2005)..
Studies of the relationship between the rise and fall of empires and the growth/decline phases of the largest cities in the same regions have found differences in the temporal relationship between the growth and decline of largest cities and largest empires. Partial correlations that take out the long-term trend show that the medium-term relationship between city and empire growth is significantly positive in Mesopotamia (2800 BCE-650 BCE), South Asia (1800 BCE-1500 CE) and Europe (430 BCE-1800 CE), but not in Egypt, West Asia, and East Asia (Chase-Dunn, Alvarez, Pasciuti and Hall 2006: Table 5.2). In the regions in which there are significant correlations this is sometimes due to the big empires building their own big capital cities, but at other times a big city appears in the region that is outside of the largest empire. This suggests that regions go through general phases of expansion and contraction in which both cities and empires grow and then decline, and this supposition is confirmed by the finding in all regions of high partial correlations between the growth/ decline phases of largest and second largest cities (Chase-Dunn, Alvarez and Pasciuti 2005: Table 5.3), and rather surprisingly, a similar set of significant positive partial correlations in all five regions studied between the growth/decline phases of largest and second largest empires (Chase-Dunn, Alvarez and Pasciuti 2005: Table 5.4). This latter is surprising because territorial growth is a zero sum game among adjacent empires, and yet the medium-term temporal correlations are positive, indicating that empires get larger and smaller together within regions. This is strong evidence that regions experience cycles of growth and decline that affect both cities and states.
The long rise of capitalism was promoted by semiperipheral capitalist city-states, usually maritime coordinators of trade protected by naval power. The Italian city-states of Venice and Genoa are perhaps the most famous of these, but the Phoenician city-states of the Mediterranean exploited a similar interstitial niche within a larger system dominated by tributary empires in the Iron Age. The niche pioneered by capitalist city-states expanded and became more predominant in the guise of core capitalist nation-states in a series of transformations from Venice and Genoa to the Dutch Republic (led by Amsterdam) and eventually the Pax Britannica coordinated by the great world city of the nineteenth century, London (Chase-Dunn and Willard 1993).
Thus the role of cities in world-systems changed greatly as capitalism became the predominant mode of accumulation over the last 500 years, and as death rates dropped precipitously over the past 200 years. In earlier world-systems the biggest cities were empire-cities based on the ability of states to extract resources using institutionalized coercion (armies, bureaucracies, etc.) Capitalist cities existed, but they were in the semiperipheral spaces between the large tributary empires. With the rise of Europe we have capitalist cities becoming the most important cities in the whole world-system. This is especially obvious with the rise of Amsterdam,London and New York – the main world cities of the capitalist era.
The Volcano Model
The first cities were residential quarters built around monumental centers. The Sumerian cities were originally organized as theocracies but, as warfare among the city-states became endemic, each found a strong king to lead them in war. Thus the central temple came to share space with the palace, often adjacent to a main gate. The first cities were oval in shape, and when walls were built for defense, they conformed to this shape. Residential neighborhoods were complex warrens of high-density housing. Square cities and grid street patterns were later inventions.
- Farming relies on supernatural
and needs priests/cultists/story tellers
=> They get a temple
- Then human enemy hordes invate
and one needs a dominant, confident, strategic and rhetorically capable king to
tell people to enter the battle field at the time he tells them to
=> The guy gets a castle
From the point of view the structure of population density both ancient and most modern industrial cities conform to the same concentric volcano model. A central non-residential district (business or monumental or both) is surrounded by concentric rings of decreasing density, with low-density suburbs as the outer ring. This is the basic structure of nearly all cities from the beginning in Mesopotamia 5000 years ago, to most cities in the world today that were built before the advent of the automobile (see Figure 1).
With the advent of mass automobile transportation the volcano model has been greatly altered, though the structure of older cities still reflects the volcano pattern. The “postmodern” (automobile) city has a different spatial structure, which is sometimes characterized as all suburb, but actually there are multiple smaller centers interspersed among the vast suburban residential, industrial and commercially specialized tracts. This is part of Michael Dear’s (2001) depiction of the transition from Chicago to L.A. as a journey to the post-modern city. The new structure is depicted in Figure 2.
There were earlier low-density cities, but they were rare. Angkor Wat, the gigantic capital of the Khmer state in Cambodia, was a city of farmlets with a large monumental center. Each residence had a tract of farmland for a yard, with canals linking a huge area. There were no high-density residential quarters. But this was an unusual exception to the volcano model.In the contemporary world older volcano cities are being surrounded and linked together by post-modern suburbs, so-called “edge cities” (Garreau 1991).
The Contemporary World City Network in World Historical Perspective
The problem of sustainable urbanization is crucial for the human encounter with the consequences of our ballooning environmental footprint. Over half of the human population of the Earth now lives in very large cities, and these have clustered and grown rapidly over the land as population densities within cities have decreased and many cities have become joined into huge city-regions that are connected by suburbanized areas. The system of world cities has been flattening as megacities in the non-core countries have caught up in terms of overall population size with the global cities of the core.
Changes in the global city size distribution, especially its flattening as megacities have emerged in the non-core, has important implications for theories of urban growth, globalization and the future of global inequalities. This section considers the conceptualization of world cities and city-regions and the idea of a global system of cities. We shall consider the global city-size distribution and the implications of its flattening for the question of the limits of settlement size and the problems of how to spatially bound cities and city-regions. And we further discuss the emergence of low density and multicentric cities.
Capitalism moved from the semiperiphery to the core, constituting a world-system in which the logic of profit making had become more important than the logic of tribute and taxation. In 1900 CE London was still the largest city, but New York was coming up fast (see Figure 4).
- The logic of information and technology will exceed the logic of money?
- Is money / financial conglomeration then capped at current 20 -40 million limit?
Within London the political and financial functions were spatially separated: empire in Westminster and money in the City. In the twentieth century hegemony of the United States these global functions became located in separate cities (Washington, DC and New York).
Despite the shift from tributary to capitalist cities, the correlation between power and the population sizes of cities continued to operate (until recently) in the modern system. Figure 2 displays changes in the city size distribution of the largest cities in the European-centered world-system since 800 CE (Chase-Dunn 1975). The city size distribution of interstate systems is almost always flatter that the size distributions of settlements within a single polity because the multicentric political structure of interstate systems affects the size distribution of settlements. Figure 2 uses the “Standardized Primacy Index,” a measure of deviation from the lognormal rule (Walters 1975). As can be seen, the Europe-centered city system is never steeper than the lognormal distribution. And it is occasionally much flatter. The periods of flatness mainly correspond with times of political decentralization in which there was an absence of a hegemonic core power (Chase-Dunn and Willard 1993).
The huge plunge into flatness from 800 to 1000 CE shown in Figure 2 was due to the shrinkage of European cities during the infeudation of Europe and the blockade of trade with Asia by the Islamic Empires. Part of the explanation for the recent descent into flatness of the world city size distribution depicted in Figure 5 is the declining hegemony of the United States. The population size primacy of New York has been challenged by the huge size of Tokyo-Yokahama. But there are also other factors at work. Cities of the semiperiphery have caught up with the largest core cities in population size and their may be operating a 20 million-size ceiling as posited by Roland Fletcher (discussed below).
Empirical studies of cycles of flatness and steepness in the city-size distribution of world-systems have tended to focus on the largest cities and to use one-parameter indicators of the shape of the distribution such as the Standardized Primacy Index in Figure 5 (e.g. Chase-Dunn and Willard 1993). Recent work by Douglas White and his collaborators uses the Q exponential function, a two-parameter scale that more precisely captures the shape of a size distribution in terms of deviation from a straight line. White et al (2006a, 2006b) use Tertius Chandler’s (1987) entire list of large cities to study changes in Q scale over time in world regions. They find an oscillation in the shape of the overall city size distribution that corresponds approximately with Giovanni Arrighi’s (1994) periodization of “systemic cycles of accumulation” and Modelski and Thompson’s(1996) “power cycles.”This supports the contention that the size distribution of cities is related to hegemonic rise and fall in the modern world-system.
Global Capitalism and World Cities
The great wave of globalization in the second half of the twentieth century has been heralded (and protested) by the public as well as by social scientists as a new stage of global capitalism with allegedly unique qualities based on new technologies of communication and information processing. Some students of globalization claim that they do not need to know anything about what happened before 1960 because so much has changed that the past is entirely incomparable with the present. Most of the burgeoning literature on global cities and the world city system shares this breathless presentism. All world-systems have exhibited waves of spatial expansion and intensification of large interaction networks followed by contractions – waves of globalization and deglobalization (Chase-Dunn, Kawano and Brewer 2000). The real question is which aspects of the most current wave are unique, and which aspects are functional equivalents of earlier pulsations. The only way to sort this out is to systematically compare the present with the past.
According to most of the theorists of global capitalism, it was during the 1960’s that the organization of economic activity entered a new period expressed by the altered structure of the world economy: the dismantling of industrial centers in the United States, Europe and Japan; accelerated industrialization of several Third World nations; and increased internationalization of the financial industry into a global network of transactions (Ross and Trachte 1990; Sklair 1992; Sassen 1991). With the emerging spatial organization of the new international division of labor, John Friedmann identified a set of theses known as the “world city hypotheses” concerning the contradictory relations between production in the era of global management and political determination of territorial interests (Friedmann 1986).
Saskia Sassen and others have further elaborated the global city hypothesis. Global cities have acquired new functions beyond acting as centers of international trade and banking. They have become: (1) concentrated control locations in the world-economy that use advanced telecommunication facilities, (2) important centers for finance and specialized producer service firms, (3) coordinators of state power, (4) sites of innovative post-Fordist forms of industrialization and production, and (5) markets for the products and innovations produced (Sassen 1991, 2000, 2001; Brenner 1998; Hall 1996; Friedmann 1995). These structural shifts in the functioning of cities have “impacted both the international economic activity and urban form where major cities concentrate control over vast resources, while financial and specialized service industries have restructured the urban social and economic order” (Sassen 1991: 4). During the 1990’s New York became specialized in equity trading, London in currency trading, and Tokyo in size of bank deposits (Slater 2004).
Beaverstock, Smith and Taylor (1999) use Sassen’s focus on producer services to classify 55 cities as alpha, beta and/or gamma world cities based on the presence of branch offices of transnational accountancy, advertising, banking/finance and law firms (See Figure 6).
The most important assertion in the global cities literature is the idea that the global cities are cooperating with each other more than the world cities did in earlier periods. The most relevant earlier period is the Pax Britannica, especially the last decades of the nineteenth century. If this hypothesis is correct the division of labor and institutionalized cooperative linkages between contemporary New York, London and Tokyo should be greater than were similar linkages between London, Paris, Berlin and New York in the nineteenth century.
Recent research on world city hierarchies uses formal network analysis methods and touts the advantages of studying actual flows and interactions among cities rather than just looking at attributes of cities. This is undoubtedly an improvement, though some of the studies only partially succeed regarding the goal of looking at interactions. The most successful in this regard is the work on air passenger flows, especially the careful research done by DeRudder et al (2005, 2006).
The city network studies by Alderson and Beckfield (2004, 2006) use the branchlocations of the world’s500 largest multinational enterprises to study the links among more than 3000 cities, and study changes in these links over time. This is a substantially different measure of city links from that constructed and used in Peter Taylor’s research on the world city network, which is based on the branch offices of transnational producer services firms following Saskia Sassen’s contention that these are the most significant actors in global capitalism. What remains to be done is to examine the relationships between these two network indicators of the global city network, and to develop a multidimensional approach to the world city hierarchy that includes political and military dimensions.
Another important hypothesis of the global cities literature is based on Saskia Sassen’s (1991) observations about class polarization and the casualization of work within globalizing cities. The research of Gareth Stedman Jones on Irish immigration into London’s East End in the mid-nineteenth century (Jones 1971) shows that a somewhat similar process of “peripheralization of the core” was occurring during the Pax Britannica. And recent research by Timberlake et al (2006) concludes that there is no significant difference between global and less global cities in the U.S. regarding the growth of income inequality in recent decades. The effects of global economic restructuring seem to affect all cities similarly.
Much of the research on the global city system has been based on case studies of particular cities that seek to identify the processes leading to their emergence and positioning within the larger system (Baum 1997; Grosfoguel 1995; Todd 1995; Machimura 1992). Janet Abu-Lughod (1999) traces the developmental histories of New York City, Chicago, and Los Angeles through their upward mobility in the world city system. While these U.S. metropoles share similar characteristics with other world cities, they have substantial differences in geography, original economic functions, transportation, and political history to serve as fascinating cases for comparative analyses of globalization.
Types of Suburbanization
From the ancient world until the industrial age most cities had a monumental non-residential center surrounded by high-density residential districts — the “volcano model” described above. Walled cities enclosed these high-density residences, but when the cities grew, suburban districts of rather lower densities formed outside of the old wall. This concentric circle pattern continued to characterize cities in the industrial age despite the geometric decline of transportation costs produced by the steam-powered railways. It was only when new cities were built during the automobile age that multicentric and low-density cities such as Los Angelesemerged (Dear 2000; 2002). The low-density and multicentric pattern is added to old concentric-style cities when they experience further growth during the automobile age – so-called edge cities (Garreau 1991).
Thus it is important to distinguish three main types of modern urban spatial macrostructure: Type A: concentric-radial cities organized around a central business district with transportation corridors radiating out from it; Type B: multicentric low density cities that are mainly “suburban” with relatively small non-residential centers dispersed across the built-up landscape (e.g. L.A.); and Type C: a mixture of these two where the older concentric structure has become edged by a newer multicentric and low-density region (so-called edge cities).
Another phenomenon of recent urbanization is the emergence of city-regions, large areas in which big cities are located rather closely to one-another and intervening areas are mainly suburbanized. Urban geographers have noted that populations in the rural areas and small towns of core countries are thinning and people are concentrating in these city regions (Scott 2001; Simmonds and Hack 2000). The city region phenomenon is made plain by examining Figures 7 and 8, maps of city lights at night produced from satellite images.
All the continents have city regions, but the largest are the eastern half of the United States and the western portion of Europe, with several other regions also displaying this phenomenon. It is important to develop a method for spatially bounding multicentric city-regions that will enable us to quantitatively compare these with one another in terms of spatial and demographic sizes, population density, and settlement size distributions and to study differences in their macrourban structures.
The Global City System
It is important to study changes in the global city-size distribution because we are interested in the relationship between cities and power, and because the apparent flattening of the global city-size distribution discovered in the 1980s raises interesting questions about the upper limits of the sizes of megacities. Why did the global city-size distribution flatten out after 1950, modifying a pattern that had existed throughout the British and U.S. hegemonies in which the most powerful country had the largest city and there was a hierarchy of city population sizes revealed by the world’s largest cities (Chase-Dunn 1985)? Roland Fletcher (personal communication) contends that contemporary institutional and infrastructural inventions only allow for megacities to function at maximum populations of around twenty millions and this serves as a kind of ceiling effect which has allowed cities in the non-core to catch up in terms of population size with the largest cities in the most powerful states. This may be what has produced the flat global city-size distribution that emerged after 1950. Another possibility that could account for cities in the semiperiphery catching up with core cities is differences in the demographic transition. Most core countries have achieved a replacement fertility rate, but semiperipheral regions still have a higher fertility rate and faster population growth. This could be a factor is allowing semiperipheral cities to catch up to core cities as regards to population size.
Fletcher’s and Modelski’s notion of an institutional upper limit on the sizes of large contiguous cities might also be part of the explanation for the emergence of city-regions rather than gigacities (the logical phase beyond megacities). Another factor that could be at work in producing the size ceiling effect is the emergence of a fairly strong environmental movement within the core. Figure 9 (above) shows Abel Wolman’s (1965) plan for delivering water from the Columbia River to Southern California. This scheme was plausible from an engineering standpoint, but is arguably now impossible for political reasons. Lack of cheap water will eventually become a limiting factor on urban growth in Southern California if other factors do not stop it first.
Another factor in the catching up of non-core cities in terms of population size is the spatial nature of the demographic transition. Core countries lowered their birth rate first and now non-core countries are catching up, but the birth rate in many non-core large cities is still high.
The size and density of city-regions are related to global differences in the level of development, and once these features of city regions are taken into account it may turn out that the global city-region-size hierarchy is related to economic and political/military power as it has been in the past. Developing countries have succeeded in building very large megacities, but their city-regions are not as large and dense as those in the core. Thus once we get the unit of analysis right, city-regions rather than single urban agglomerations, the older association between power and settlement size that characterized the world city system for centuries, may turn out to have survived into the current era.
Cities and the Future
About half of the over six billion people on Earth now live in very large cities. Of course, large cities are not all the same. Many of the large cities of the non-core have huge slums where life is tenuous (Davis 2006). Inequalities within and between countries have increased during the most recent wave of globalization, just as they did in the 19th century wave (O’Rourke and Williamson 2000). The low-density suburban sprawl that has taken over the process of urban growth in the core is immensely expensive in terms of resource use. And urbanization has a huge direct effect on the environment. The materials of which cities are built absorb heat from the sun and then release it at night. And the consumption of energy in cities contributes to global warming. The “urban heat island” is an important phenomenon that is contributing to global climate change (see Figure 10)
While core cities have deindustrialized, large cities in the semiperiphery have industrialized and are now the new sites of intense labor struggles (Silver 2003). The global “reserve army of labor” (people still not employed as wage labor in the formal economy) is still large, but continued economic expansion and globalization will eventually incorporate everyone, and the long-run tendency for wages to rise will continue, eventually causing a crisis for capitalism (Wallerstein 2004).
Peter J. Taylor (2003) contends that globalization has decreased the importance of nation-states and increased the importance of cities, and that this may be a good thing because cities are more easily governable by communities of citizens. Human settlement systems have been strongly involved in the evolution of world orders for thousands of years as both cybernetic nodes of innovation, and in the process of semiperipheral development. Regarding the latter, we can expect that new forms of governance relevant to solutions of the emergent problems of the twenty-first century will likely be invented and implemented in the cities of some of the semiperipheral countries, e specially Brazil, India, Mexico and China. Curitiba, Brazil has already demonstrated a new form of sustainable urbanism that will become increasingly relevant as the fossil fuels that have been the basis of sprawl become depleted (Rabinovich and Leitman 1996)). Democratic socialist regimes that come out of the new labor movements of the semiperiphery are likely to be important supporters of transnational social movements that will contest neoliberal (and neoconservative) global governance and push toward a new kind of globalization from below. The cities of the semiperiphery are fertile spaces for finding solutions for our increasingly urbanized planet.