Abstract
From the research of people like William Garrison (geography, planning) and Harrison White (anthropology, sociology), various aspects of graph theory and network analysis—addressing accessibility and centrality of nodes, allocating new observations to groups or regions, and assigning flows to route paths—became known to social scientists by the late 1960s (Haggett & Chorley, 1969). Other studies, using matrix algebra, revealed how different processes might unfold over time across demographic, social, and economic systems (Gale, 1960; Keyfitz, 1977; Rogers, 1971). Subsequently, the network perspective has shed much new light on a variety of socioeconomic issues at the urban (or metropolitan) scale, including the matching of supply and demand in regional labor markets; the effects of first-, second-, and higher-order adjacency in spatial estimation; the price and location adjustments of spatial rivals in retailing; the nature of differential ties in migration streams and acquaintanceship circles; the role of hierarchy in the decisions, transactions, and information exchanges of agents; and the sizes of input–output multipliers in both intra- and interregional settings.
The modern study of connectivity among global cities began in earnest with Peter Hall’s reflections on the employment shifts recently seen in very large and influential places—especially London, New York, Paris, and Tokyo—where, by the 1970s, nearly all traditional manufacturing had departed “offshore,” most routine services had migrated to the suburbs or beyond, and various high-level functions (including producer and financial services), all still dependent on face-to-face contact and cheap communications, were becoming increasingly dominant (Hall, 1966). Follow-up research by John Friedmann, Saskia Sassen, Peter Taylor, and others traced the features and implications of these changes; here, Allen Scott (2001) provides a very useful summary. In the past two decades, global research has focused more on the various ways that public and private agents (e.g., firms, research labs, and universities) unevenly interact across space, both within and among large cities (Brenner, 2019; Storper et al., 2015). Until COVID-19, the general background was a period of ascendant globalization, albeit one with pauses, where the behaviors of agents evolved but generally adapted over time, even with the emergence of new and disruptive transportation and communications technologies (Baldwin, 2016).
This Handbook, comprised of 29 chapters spread over five sections, is edited by Zachary Neal, a psychologist, and Céline Rozenblat, a geographer. The 53 contributors come from 14 nations, including the United States (20), United Kingdom (12), Australia (3), People’s Republic of China (3), France (3), and nine others (12). The disciplinary homes of these scholars are not noted but many have been drawn from the classics, spatial sciences (geography), mathematical ecology, and physics. Economists, perhaps trained in cliometrics, appear to constitute a surprisingly small minority. The book is sensibly organized, the writing is well edited, the mathematics is kept to a minimum, and the various discussions are usefully supplemented with numerous figures, many of which are in color. A hard copy print, whose price exceeds $300, is expensive but an e-copy, priced near $30, is entirely reasonable.
General Issues
The first section of the Handbook opens with an informative chapter by Denise Pumain. After introducing some lesser-known (European) studies about cities, she returns to her earlier observation that cities simultaneously evolve according to both territorial and reticular principles. Echoing some of the early work on geographic diffusion, she states that spatial proximity dominates in the first case and hierarchical positioning dominates in the second. Great cities, like Chicago, are somehow able to make a transformation in their economic base from the first to the second principle—often by controlling a cost-saving means for transportation and communications—and they continue to thrive along both lines (Cronon, 1991). More of this theme is taken up by Luis Bettencourt, who argues there are (at least) four key agents that operate simultaneously, at different scales, across the embedded networks of highly urbanized postindustrial societies; in ascending size and complexity, these agents are the individual, the neighborhood, the city, and the city system. Bettencourt also provides a cogent summary of the determinants of the reproductive number, which controls the timing and spread of epidemics in susceptible populations. Older regional scientists will recall the similar, but less analytical, studies carried out on these and related topics by people like Brian Berry, Manuel Castells, Peter Gould, and Allan Pred.
In the next section of the Handbook, Elizabeth Bogumil and Christopher Chase-Dunn provide a somewhat different perspective by viewing the uneven rise of the world-city network as a salient feature of post-1970 neoliberalism, which replaced the Keynesian development model. World cities became control centers for advanced capitalism once large multinational firms came to dominate, and then homogenize (and often rationalize), media output and financial services while, at the same time, came to coordinate if not usurp many traditional state powers. So, in a sense, the North Atlantic doctrine of neoliberalism eventually led to the proliferation of large megaregions—as John Gottmann first noted in the early 1960s. Jack Hanson then follows with an interesting case study of early urbanism focusing on the Mediterranean basin. His perspective is that large cities developed both immediate hinterlands (for necessities) and distant trading partners (for luxuries) in an early “world-city network,” and that, once large places like Rome and Alexandria could no longer cover their deficits suffered in some areas with the earnings gained in others, such important centers went into sharp decline and, soon thereafter, their hinterlands suffered the same fate. In short, he claims that this early world-city network first overreached and then imploded.
In the third section of the Handbook, Marc Barthelemy examines the properties of those physical networks that are embedded in urban space. Here, echoing the recent thoughts of Geoffrey West on scale, he exposes some of the mathematics used to address networks, and uses log regression to show that the length of a physical (e.g., street, water, and sewage) network is invariably an exponential function of city size. However, many social scientists will be less interested in the goodness-of-fit and more interested in the variation of the intercept (perhaps reflecting age difference) and slope (population density difference) estimates in the various models. The author also attempts to classify urban street patterns according to their shapes and sizes. Again, the “fingerprints” of urban street patterns might be grouped differently if other clustering algorithms were applied. In any case, Barthelemy (p. 144) himself calls for more work to draw out such a “quantitative and systematic comparison” of physical and social networks.
Intraurban Issues
The next section of the Handbook assembles nine chapters that (mainly) address network patterns and processes within cities. Here one of the more interesting chapters addresses the formation of social groups, or coalitions, in large places. Brian Christens and Daniel Cooper distinguish between interpersonal and interorganizational networks in discussing how different coalitions—both civil and non-civil—are formed based on mutual understanding, trust, and a shared commitment among each group’s members. Special attention is given to the Right on Justice coalition in Chicago, which combines both grassroots organizations and other groups seeking more resources for young people of color. Graphs and network maps are used to indicate whether the various constituencies are converging around a shared philosophy (Coleman, 1990). In another chapter, Michael Batty explores the application of Markov chains in effecting conflict resolution among diverse parties. He argues that networks not only exist for physical movements and administrative purposes, but they also mediate in the creation and subsequent transmission of data, ideas, and other information. In a third chapter, Susan Burtner and Alan Murray examine recent commuting patterns in Los Angeles (Los Angeles and Orange counties). Instead of indexing segregation according to the presence and absence of counts in various subregions (318 neighborhoods), they look instead at the attributes of daily trips made by individuals for all purposes. Four separate racial groups are profiled where neighborhood-interaction potential matrices summarize how likely it is for one racial group, on average, to encounter another during its array of daily journeys. Whites and Hispanics travel to nearly every neighborhood across the counties; however, Blacks (and African Americans) travel to only one-half and Asians to only two-thirds of those neighborhoods. Clearly, these two groups do not participate in, or benefit from, the various advantages, resources, and services that are available to them throughout the entire city.
Interurban Issues
The final section of the Handbook (mainly) devotes a further eight chapters to network patterns and processes among interacting cities. Here Ben Derudder and Taylor update the GaWC data (see the global cities website at Loughborough University) and respond to some of the various criticisms this research group has already engendered. A roster of 172 cities, drawn from more than 700 places that were either capitals or whose population exceeded 1.5 million in 2014, was defined and ranked according to the importance of five types of private business activities (e.g., accounting, management). The ensuing connectivity index reveals that traditional north–south economic gaps have been reproduced and suggests that uneven globalization has, in turn, ensured an uneven distribution of connectivity among the world’s preeminent cities. In some nations, especially notable in Scandinavia, capital (or primate) cities still heavily dominate business connectivity to major outside cities; but, besides the rising control centers of China, there is evidence that places like Dubai and Mumbai are ascending the world’s “connectivity ladder” very quickly. The exercise is repeated with the addition of nongovernmental organizations and the “spiked” world map of connectivity scores is flattened out to a remarkable degree. Now Washington and Brussels emerge as major players in the world’s core regions and Nairobi and Lima, among several others, emerge in the world’s periphery. The instability seen in these global connectivity patterns indicates that some sort of multivariate analysis is needed to reduce the redundancy that occurs in the estimation of city-specific connectivity levels. In a related chapter, Ronald Wall and Umakrishnan Kollamparambil address some determinants of international income and wealth disparities using a world cities perspective. When cities are spatially isolated from other cities, they tend to exhibit higher Gini indices, but when they are tightly integrated with others the Gini index falls. Also, consistent with some well-known findings of (modern) trade theory, functional similarity (economic closeness) to other cities tends to reduce the income or wealth inequalities seen in metropolitan economies. Again, though, any covariation that might persist across physical and economic distancing is not addressed, and it is likely that estimates could be sharpened by adjusting for spatial dependency in the regression models.
Closing Remarks
Like nearly all Handbooks it is unfortunate that no overarching summary chapter is provided by the editors. At the very least it would be helpful to identify those general directions for research that seem to be the most promising. One line of study might focus on how individual cities and city systems co-evolve as national population densities thicken and control technologies improve. Various observers have stated that global cities often have much more in common with one another than with other cities in their respective national hierarchies. But some of the economic growth experienced by these global cities—at least in their earliest stages of development—is invariably derived from assuming dominance in those national hierarchies. Also, following ideas expressed in the early work of David Harvey, more clarification might be made between relative space and relational space in affecting the behavior of urban agents. Depending on their mixes of ages, values, occupations, and the like, two social groups, or communities, can exhibit very similar relative (adjacency) properties but somewhat different relational (functional) properties. Once aggregation has been carried out across the chosen agents in separate groups, the adoption of Torsten Hägerstrand’s time geography model might reveal key differences existing in macrobehavior for the two conceptions of urban space. Clearly, not all these differences will emerge if standard spatial-econometric measures are taken to control only for the various locations (coordinates) of these agents.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
