This Research Bulletin has been published in Urban Studies, 43 (11), (2006), 2027-2046.
Please refer to the published version when quoting the paper.
Peter Taylor (2004) has recently argued that the “world city literature” as a whole has been characterized by “theoretical sophistication and empirical poverty” (p. 33), whereby one effect of this “evidential crisis has been the failure for there to emerge any agreement on just which cities are world or global cities and which fail to qualify” (p. 39). This clearly comes to the fore in a comparison of 16 different rankings of “world cities, global cities, and international financial centres from different sources” (pp. 39-41). Taylor (2004, p. 39) notes that there are only four cities all 16 studies agree upon (London, New York, Paris, and Tokyo), while there are seventy-eight other cities that at least one source names in its ranking. This profound disagreement, Taylor (2004, p. 39) thereupon suggests, reflects the failure of this literature to provide precise empirical specifications of the various concepts.
Although there has indeed been a lack of precise specifications, I would argue that it is doubtful whether this shortage can be asserted on the basis of an apparent disagreement on which cities qualify as ‘global cities’, ‘world cities’ or ‘international financial centres’. After all, Saskia Sassen (2001a, p. xix) reminds us that “there may well be some global cities today that are not world cities in the full, rich sense of that word.” Put simply: global cities and world cities are apparently not the same phenomenon, and there is therefore no reason why their geographies should converge. In other words, the profound differences in the 16 studies listed by Taylor (2004, pp. 39-41) are not necessarily a sign of inadequate empirical operationalizations, they may simply reflect the diverging spatialities of different concepts.
The general purpose of this paper is to illustrate that Taylor’s decision not to distinguish between different concepts is emblematic for a baleful tendency in the ‘world city literature’ a large. Olds and Yeung (2004, p. 515) and Brenner (1998, p. 29), for instance, start their article with a footnote in which they state that the terms ‘world city’ and ‘global city’ will (and hence can) be used interchangeably1. Although the basic contention of the present paper is that this may be a problematic move, I aim to move well beyond emphasizing the importance of more terminological rigor. I will try to show that such a loose use of terms may merely be the surface-level manifestation of a series of more profound conceptual conflations. Hall (2001, p. 61), for instance, goes beyond employing the various terms interchangeably by maintaining that “the various approaches” covered by these terms “are perhaps not quite as distinct as they may seem.” The main point here is that there are myriad such declarations in the literature, which suggests an overarching trend to systematically downplay and/or even outright ignore the analytical peculiarities of different concepts. To be sure, these peculiarities may sometimes be of secondary importance, but I will argue that there are equally instances in which the differences between concepts cannot be so easily dismissed. More specifically, in this paper, I will focus on the way in which a lack of conceptual rigor has devalued the analytical merits of some recent empirical analyses.
This paper is divided in three main sections. First, I briefly sketch how researchers have recently tried to map a transnational urban network. To this end, I construct a taxonomy of empirical approaches that distinguishes between (i) studies that have used data on infrastructure networks (e.g. airline networks) and (ii) studies based on information on corporate organization (e.g. the organizational structure of multinational enterprises). Virtually each of these empirical studies has, of course, tried to assert its relevance by referring to various theoretical contributions, and in the second section I therefore discuss and contrast the defining tenets of the two dominant concepts, i.e. ‘world cities’ and ‘global cities’. The main conclusion of this overview is that these terms cover analytically distinct concepts. In the third section, then, I show how recent empirical studies have (to a varying degree) downplayed this need to distinguish between different concepts. I focus on four entwined examples: (i) the loose use of terminologies in empirical studies (e.g. addressing an empirical analysis of global cities in terms of world cities); (ii) comparing analytical features of different concepts (e.g. casting doubt on the alleged structure of a network of global cities on the basis of an empirical study of a network of world cities); (iii) the fuzzy delineation of the urban area (e.g. interpreting the dynamic of global city formation in terms of the wider region); and (iv) the poor analytical value of infrastructure-based analyses (e.g. airline data being capable to empirically capture all concepts in a single analysis). Taken together, I conclude, these four types of conceptual confusion reveal that more analytical thoroughness is required in this body of literature.
II. Empirical Approaches
Throughout the last two decades, a number of researchers have analyzed the emergence of a transnational urban network centred on a number of key cities in the global economy. Some of the conceptualizations of this urban network have thereupon been used in empirical studies, which have sought to sketch the network’s basic contours. Almost a decade ago, Short et al. (1996) signalled that, taken together, these empirical studies were flawed by a number of obstacles. The obstacle that has received most attention to date is, of course, the lack of ‘suitable’ data. Indeed, since Short et al.’s (1996) identification of this ‘dirty little secret’, it has become commonplace to bemoan the paucity of relevant data in this context, whereby most commentators specifically target the lack of data on actual inter-city relations (e.g. Knox, 1995, 1998; Beaverstock et al., 1999, 2000a,b; Smith and Timberlake, 1995a,b, 2001, 2002; Taylor, 1997, 1999, 2000, 2004; Hall, 2001; Alderson and Beckfield, 2004; Derudder and Taylor, 2005; Derudder and Witlox, 2005a). Alderson and Beckfield (2004, p. 814), for instance, observe that hardly any of the empirical studies “have utilized the sorts of relational data necessary for firmly establishing such rankings empirically,” while Knox (1998, p. 26) maintains that “few of the available data reveal anything about the flows and interdependencies” that are at the heart of this body of literature. At the most basic level, this enduring quest for relational data stems from the observation that, in a networked context, important cities derive their status from what flows between them rather than from what remains fixed within them (e.g. Amin and Graham, 1999; Allen, 1999; Castells, 2001).
In the past few years, we have witnessed a proliferation of empirical studies that explicitly seek to rectify this ‘empirical conundrum’ (Taylor, 2001) by devising datasets that take on the form of ‘cities in global matrices’ (Smith and Timberlake, 1995a,b). Researchers have, of course, relied on a wide variety of data sources to fill these ‘global matrices’. Generally speaking, the production of these databases has been premised upon two foundations, which may respectively be labeled (i) the corporate organization and (ii) the infrastructure approach2 (Table 1). The corporate organization approach starts from the observation that relations between key cities are primarily created by firms pursuing transnational location strategies, whereas the infrastructure approach focuses on a series of enabling infrastructures that underpin border-crossing urban networks. In any case, it is claimed that the spatiality of these corporate or infrastructure networks may shed light on the geographical outline of a transnational urban network.
The corporate organization approach starts from the observation that firms pursuing global strategies are the prime agents in the formation of urban networks. Two leading examples are the research pursued by the Globalization and World Cities group and network (GaWC, http://www.lboro.ac.uk/gawc) and a recent analysis by Alderson and Beckfield (2004). GaWC-researchers have developed a methodology for studying transnational urban networks based on the assumption that advanced producer service firms ‘interlock’ cities through their intra-firm communications of information, knowledge, plans, directions, advice, etc. to create a network of global service centers (Taylor, 2001). Building on this specification, information was gathered on the location strategies of 100 global service firms across 315 cities (Taylor et al., 2002a). Applying the formal social network methodology set out in Taylor (2001), this information was converted in a 315 x 315 matrix, which was then analyzed with standard network-analytical tools (Derudder and Taylor, 2005).
Using a similar methodological approach, Alderson and Beckfield (2004) have analyzed links between 3,692 cities based on the organizational geographies of 446 of the largest multinational firms and their subsidiaries for the year 2000. Despite some methodological differences (Taylor, 2005), both studies base their city-centered spatial analysis on an assessment of the location strategies of firms with transnational fields of activity. In other words, it is suggested that a meaningful measurement of transnational inter-city relations can be derived from intra-firm connections between different parts of a firm’s holdings: Alderson and Beckfield (2004, pp. 813-4) consider this to be a “key relation” in “an MNE-generated city system”, while Taylor (2004, p. 59) argues that it is “firms through their office networks that have created the overall structure of the (…) network.” The main difference between both approaches lies in the type of firms used throughout their analysis: GaWC-researches focus on the location strategies of producer services firms, Alderson and Beckfield (2004) use information on the geography of multinational corporations irrespective of the exact nature of their activities (e.g. their table of the distribution of firms ‘across industries’ on p. 821).
The gist of the infrastructure approach lies in the observation that advanced telecommunication and transportation infrastructures are unquestionably tied to key cities in the global economy. The most important cities also harbor the most important airports, while the extensive fiber backbone networks that support the Internet have equally been deployed within and between major cities, hence creating a vast planetary infrastructure network on which the global economy has come to depend almost as much as physical transport networks (Rutherford et al., 2004). These enabling (tele)communication and transportation networks are the fundament on which the connectivity of key cities is built, and it is therefore no surprise that the geography of these networks has been used to invoke a spatial imagery of a transnational urban network. Smith and Timberlake (2002, p. 139) , for instance, have sought to describe the spatial patterning of a transnational urban network “as indicated by their interrelations in the air passenger networks”, while Moss and Townsend (2000, p. 36) have presented an analysis based on the observation that “major urban centres have emerged as key participants in the network of data nodes and flows that mediate the transactions of an integrated global economy.” Both analyses claim that it is possible to empirically devise an urban network based on the geography of infrastructure networks, whereby the main difference between both approaches lies in the type of infrastructure, i.e. telecommunications versus physical transportation.
Table 1: Taxonomy of main empirical approaches.
III. Theoretical Approaches
For one thing, the various theoretical conceptualizations of a transnational urban network are loosely united in their observation that cities such as New York and London somehow derive their importance from a privileged position in networks of capital, information, and people. Furthermore, most concepts have a common focus in that they (i) point to the effects of the increasing internationalization of trade and production, (ii) give some weight to the increased service intensity in all sectors of economic life, and (iii) identify the relevance of recent evolutions in telematics. However, at the same time, it is quite obvious that an all-purpose approach rings rather hollow. Acclaiming the relevance of studying cities in the context of a transnational urban network may be acceptable for pedagogic or even heuristic reasons, but it most certainly needs further specification if it wishes to have some analytical value3.
Take, for instance, the way in which Saskia Sassen has presented her influential ‘global city’ concept. It is clear from the outset that Sassen wishes to develop a new concept rather than refining existing ones. In the introduction to the revised edition of The Global City, Sassen (2001a, p. xxi) maintains that “[w]hen I first chose to use [the term] global city I did so knowingly – it was an attempt to make a difference.” This attempt to discriminate between concepts is further specified John Friedmann’s ‘world cities’. Sassen (2001a, p. xxi) stresses that it may be the case that “most of today’s major global cities are also world cities,” albeit that there may just as “well be some global cities today that are not world cities in the full, rich sense of that term”4. The major implication for the present discussion is that the variety of terms used to describe a transnational urban network is not a trivial matter of semantics. The most commonly employed terms in this body of research, such as ‘global cities’ (Sassen, 2001a), ‘world cities’ (Friedmann, 1986), ‘global city-regions’ (Scott, 2001a,b), ‘globalizing cities’ (Short, 2004), ‘the globalized city’ (Moulaert et al., 2003),... may very well share the basic connotation of ‘important cities in the context of an increasingly globalizing economy’, but in practice they may cover divergent concepts.
In the next paragraphs, I will try to single out the analytical core of the two concepts that can, according to Taylor (2004, p. 21), be conceived as “key contributions” in “this new school of research,” i.e. the concepts developed by Friedmann (1986, 1995) and Sassen (2000, 2001a)5. The discussion primarily focuses on four features of each conceptualization, i.e. (i) the main function of cities, (ii) the key agents in formation of the urban network, (iii) the alleged structure of the urban network as a whole, and (iv) the territorial demarcation of the urban area.
III.2. Friedmann’s World Cities
The world city concept can be traced back to two interrelated papers by Friedmann & Wolff (1982) and Friedmann (1986)6 . Both texts framed the rise of a transnational urban network in the context of a major geographical transformation of the capitalist world-economy. This restructuring, most commonly referred to as the ‘New International Division of Labor’, was basically premised on the internationalization of production and the ensuing complexity in the organizational structure of multinational enterprises. This increased economic-geographical complexity, Friedmann (1986) argues, requires a limited number of control points in order to function, and world cities are deemed to be such points. The territorial basis of a world city is hereby more than merely a CBD, since “[r]eference is to an economic definition. A city in these terms is a spatially integrated economic and social system at a given location or metropolitan region. For administrative purposes the region may be divided into smaller units which underlie, as a political or administrative space, the economic space of the region” (Friedmann, 1986, p. 70). This implies that world cities are, in fact, more often polycentric urban regions rather than central cities, hence Friedmann’s (1995) designation of Kansai Region, Randstad Holland and the Ruhr Area as world cities. These polycentric urban regions can be more formally defined as follows (Kloosterman and Lambregts, 2001, pp. 718-719):
Randstad Holland can be seen as a prime example of such a polycentric urban region with relatively strong functional relationships. The Randstad is built around four major cities (Amsterdam, Rotterdam, The Hague and Utrecht) together with a number of smaller cities in the western part of the Netherlands. The major implication here is that the proper unit of analysis in the light of the world city concept is the Randstad as a whole rather than Amsterdam or Rotterdam on their own terms.
Friedmann (1986, 1995) tries to give theoretical body to his ‘framework for research’ by subsuming it under Wallerstein’s world-systems analysis, hence the title of Knox and Taylor’s (1995) World Cities in a World-System and the hyphen in ‘world-economy’ (see also Saey, 1996; Taylor, 2000; Derudder, 2003). As is well known, Wallerstein (1979) envisages capitalism as a system that involves a hierarchical and a spatial inequality of distribution based on the concentration of relatively monopolized and therefore high-profit production in a limited number of ‘core’ zones. The division of labour that characterizes this spatial inequality is materialized through a tripolar system consisting of core, semi-peripheral and peripheral zones. The prime purpose of world city research, now, is that it seeks to build an analytical framework that searches to deflect attention from the role of territorial states in the reproduction of this spatial inequality (Brenner, 1998, p. 4)7.
In other words: despite “ being largely studied through its mosaic of states (...) the modern world-system is defined by its networks” (Taylor, 2000, p. 20), and world cities are the nodes in such networks of power and dominance. Apart from being the economic power houses of the world-system, world cities are also locales from which other forms of command and control are exercised, e.g. geopolitical and/or ideological-symbolical control over specific (semi-)peripheral regions in the world-system. Miami’s control position over Central America is a case in point here (Grosfoguel, 1995). Friedmann (1986, p. 69) reminds us, however, that “the economic variable” is “likely to be decisive for all attempts at explanation.” Major importance attaches hereby to a limited number of rapidly expanding sectors, such as “corporate headquarters, international finance, global transport and communications; and high level business services, such as advertising, accounting, insurance, and legal services.” It is, however, clear that the presence of corporate headquarters (both global and ‘regional’, see Godfrey and Zhou, 1999) is analytically more important than the presence of a business services sector and/or a well-developed infrastructure, since the latter are necessary but not sufficient variables in the formation of a network of world cities.
III.3. Global Cities
In her book The Global City, Saskia Sassen (1991/2001a) proposes to look afresh to the functional centrality of cities in the global economy, and does so by focusing upon the attraction of producer service firms to major cities that offer knowledge-rich and technology-enabled environments. In the 1980s and 1990s, many such service firms followed their global clients to become important MNEs in their own right, albeit that service firms tend to be more susceptible to the agglomeration economies offered by city locations. These emerging producer service complexes are at the root of a new concept of urban centrality in the world economy: global cities.
Sassen’s global city concept thus advocates a shift of attention to the advanced servicing of worldwide production. >From a focus on formal command power in the world-system, the
“emphasis shifts to the practice of global control: the work of producing and reproducing the organization and management of a global production system and a global market-place for finance (...) Power is essential in the organization of the world economy, but so is production: including the production of those inputs that constitute the capability for global control and the infrastructure of jobs involved in this production” (Sassen, 1995, pp. 63-64, her emphasis).
Through their transnational, city-centered spatial strategies, producer service firms have created worldwide office networks covering major cities in most or all world regions, and it is exactly the myriad of connections between these service complexes that gives, according to Sassen (2001a, p. xxi), way to the “formation of transnational urban systems.” This urban network, Sassen (1994, p. 4) argues, results in a new geography of centrality that may very well cut across existing North/South divides. Hence, rather than reproducing existing core/periphery patterns in the world-economy, this network may break through these divides.
This focus on urban agglomeration has a major implication for the territorial demarcation of global cities. R ather than being structured in mutual dependence to a hinterland, as assumed in more classical versions of central place theory, the functional centrality of global cities becomes “increasingly disconnected from their broader hinterlands or even their national economies” (Sassen, 2001a, p. xxi). One can for instance observe that “[t] he downtown section of New York City is deeply connected to the downtown section of São Paulo, much more than the downtown of São Paulo is to its own periphery” (Sassen, 1997, p. 3). New York City as a global city, therefore, is the ‘five burroughs’ rather than the metropolitan region, while Tokyo is the ‘Tokyo Metropolis’ rather than the larger ‘Tokyo Metropolitan Region’ or the ‘National Capital Region’ (Sassen, 2001a, p. 371). All in all, it is obvious that Sassen (2001b, p. 80) opts “for an analytical strategy that emphasizes core dynamics rather than the unit of the city as a container–the latter being one that requires territorial boundary specification.” This does not necessarily imply that the functional centrality in global cities is a simple continuation of older centrality patterns, since the territorial basis can consist of “a metropolitan area in the form of a grid of nodes of intense business activity, as we see in Frankfurt and Zurich” (Sassen, 2001a, p. 123; note, however, the lasting importance of the Midtown and Wall Street Area in New York City). That said, it is clear that the proper unit of analysis may very well be smaller than the ‘metropolitan region’.
III.4. Overview and Discussion
Table 2 summarizes the gist of the ‘world city’ and the ‘global city’ concept. I have, of course, been very sketchy in my treatise of both concepts. Some claims are undoubtedly open for debate, while refinements and revisions have been presented elsewhere. However, it seems fair to state that this discussion gives a balanced overview of the conceptual core of both approaches: Friedmann envisages global urbanization in terms of dominance and power, while Sassen emphasizes that global urbanization should be conceived in terms of the production of the inputs that constitute the capability for global control. These different starting points thereupon give way to diverging perspectives on the main features of global urbanization: a city’s prime function as node in transnational networks, the key agents in these networks, the spatial structure of the global capitalist system (and its alleged consequences for the structure of the global urban network), and the territorial basis of the city-as-node. One of the major implications of Table 2 is that the various terminologies recently highlighted by Taylor and Lang (2004) may reflect very diverging perspectives on how we can understand the phenomenon of globalized urbanization.
Thus, although one can argue back and forth on the profoundness of the differences summarized in Table 2, it seems obvious that there is an unambiguous need to distinguish between different concepts. Friedmann and Sassen have, for instance, a very different take on the relationship between global capitalism and global urbanization. For Friedmann, the key issue lies in investigating the spatial distribution of (economic) power in the current phase of the capitalist world-system. Power is increasingly centralized in large scale urban regions, Friedmann notes, and he therefore proposes to investigate the dynamics of this worldwide urban network as an alternative to analyses of dynamics of the inter-state system. Hence, the issue of economic power in the global capitalist system leads Friedmann to centrality. Sassen, in contrast, primarily aims to understand centrality in the digital era. Graham (1998, pp. 168-170) presents an extensive overview of visionary statements that predict that the digital era will prove inhospitable to the high density city. These new technologies, it is argued, will soon begin to provide excellent substitutes for face-to-face contact. Such statements, however, are undermined by the observation that a set of important cities are by and large actually thriving at the present time. Sassen spells out the reasons for this, and essentially suggests that the production process in advanced service industries involves the creation of central places that are located in global networks. Hence, the issue of centrality leads Sassen to the production of (economic) power in the global capitalist system. This crucial bifurcation thereupon guides Friedmann and Sassen to very different analytical frameworks, as Table 2 shows.
Unlike geographical analyses of the inter-state system, for instance, which have the advantage of having more or less stable units of analysis, the demarcation of cities is surrounded by a fair amount of ambiguity (think of the question of urban sprawl, conurbations and so on). Sassen’s focus on centrality leads here to conceptualizing ‘global cities’ as focal points that operate separately from their hinterlands (mostly downtown areas). Friedmann’s focus on the relative concentration of power in contrast, implies that a ‘world city’ may consist of multiple cities and their hinterlands that may themselves be subject to urbanization processes. Put succinctly: the Pearl River Delta and Randstad may very well be a ‘city’ in Friedmann’s framework, but these large scale urbanized regions will most likely not be considered a ‘city’ by Sassen (Hong Kong and Amsterdam in and by themselves will most likely be the unit of analysis here).
Another important difference lies in the anticipated structure of the urban network. Friedmann envisages a network of world cities as a system that enables the continuation of existing core/periphery-patterns in the global capitalist system. Sassen, in contrast, conceives a network of global cities as a distinctively new system that may cut across the inter-state divides in the global capitalist system. Thus, for instance, a ‘semi-peripheral city’ such as Jakarta may not be considered to be an important city when one focuses on (economic) power, but it may very well be that it is a rather strongly connected node in an emerging system of global service centers. Conversely, a secondary European city such as Utrecht will by no means be named as an important service center in transnational terms, but it may very well be conceived as a formative part of a polycentric urban region (Randstad Holland) that functions as a major power house in the global capitalist system.
For one thing, then, an empirical analysis of the global urban network depends heavily on the perspective of what constitutes and drives global capitalism and global urbanization. In terms of the two dominant approaches highlighted in this paper, this simply implies that rankings of world cities and global cities may be expected to diverge rather than converge. E.g., it is not unlikely that Jakarta will rank fairly high in a global city ranking and fairly low in a world city ranking, while Utrecht will not feature in a global city ranking but may show up in an analysis of world cities as formative part of a large scale urban region centered on Amsterdam, Rotterdam, The Hague and Utrecht.
Table 2: Taxonomy of main theoretical approaches.
*: The spatial demarcation depends on the specific form of the territorialization of the core dynamics behind global city-formation. This implies that both the continuation of traditional CBDs ( New York) as a new pattern centered on a grid of intense business activity (Zürich) is possible. However, the proper unit of analysis is clearly smaller than the ‘metropolitan region’ as a whole.
IV. Discrepancies Between Theory and Measurement
Taken together, the taxonomies of the main empirical approaches (Table 1) and the most important theoretical contributions (Table 2) allow assessing the lack of analytical rigor in recent empirical studies. It is obvious that the possible discrepancies between theory and measurement are manifold, and this discussion is therefore divided in four separate (but entwined) paragraphs. The first paragraph presents a simple review of the inadequate use of terms in the recent empirical literature. The three other paragraphs take the discussion beyond this mere terminological critique by focusing on some analytical ambiguities in recent empirical studies. The second paragraph is devoted to an in-depth analysis of how results of empirical studies are framed against the background of other concepts. The third paragraph deals with the problem of delineating the units of analysis in empirical studies. In the latter two paragraphs, I will mainly focus on one of the most detailed empirical analyses to date, i.e. the network analysis by Alderson and Beckfield (2004). This section should, however, not be read as a critique of this specific paper – this detailed review merely allows fleshing out some problems that seem to be representative for a broader tendency. The fourth paragraph assesses the poor conceptual basis of infrastructure analyses.
IV.1. Discourse Analysis
The somewhat obvious starting point for this assessment is a simple verification of the employed terminologies in recent empirical studies (Table 3). In addition to references to ‘world cities’ (WC) and ‘global cities’ (GC), I have also indicated references to the demographic significance of cities (MC), such as ‘large cities’, ‘mega-cities’, and so on. Obviously, the table is primarily based on the directly used discourse, but there are equally some references that are based on more implicit allusions. A case in point is Derudder et al. (2003), who present a global urban analysis of 234 cities based on the data gathering in Taylor et al. (2002a). With the exception of a single mentioning of ‘global cities’ (Derudder et al., 2003, p. 885), the authors employ the term ‘world city’, but it is quite clear that ‘global cities’ are deemed to be at least as relevant. For instance, Derudder et al. (2003, p. 877) ascertain that they follow “Sassen in her treatise of cities as global service centers – locales where advanced producer services are concentrated for servicing their global corporate clients.”
Furthermore, it is important to note that not all studies mentioned in Table 3 have explicitly sought to map a transnational urban network: (i) some studies encompass another scale of analysis, while (ii) other researches have a somewhat different motivation. (i) Rodríguez-Pose and Zademach (2002, p. 1911), for instance, examine the influence of mergers and acquisitions on the German urban system. However, at the same time, they ascribe some relevance to their analysis on a supra-national scale by suggesting that their results present “a panorama close to that pictured by Sassen and Taylor.” (ii) The essence of the studies by Townsend (2001) and Malecki (2002), in turn, lies in highlighting the spatial contingency between the Internet backbone and important cities. However, by doing so, they maintain that their results make it possible “[t]o illustrate how global cities have fared in the rapid and massive deployment of Internet networks” (Townsend, 2001, p. 1700) and to set “the spatial agglomeration of linkages and linkage sites (...) in the context of the urban hierarchy of world cities” (Malecki, 2002, p. 400). While it is clear that such studies cannot assume a prominent position in this discussion, their inclusion in Table 3 seems warranted on the basis of their references to theoretical contributions on the formation of a transnational urban network.
The studies carried out within the corporate organization approach have a comprehensible conceptual background, and it is therefore straightforward to pin down what terms should be referred to: studies drawing on the location strategies of producer service firms pertain to processes of global city-formation, while studies employing data on the organizational structure of large MNEs refer to world city-formation. It is less obvious to what concepts infrastructure-based studies refer. In paragraph IV.4, I will argue that because of the general character of the captured flows and the broad territorial basis in the generation of flows, these data cannot differentiate between ‘world cities’ and ‘global cities’, and may therefore be less relevant in this context than commonly assumed.
Thus, in Table 1, Derudder and Taylor (2005) measure a network of global cities, Alderson and Beckfield (2004) quantify a network of world cities, while it is unclear to what concept Smith and Timberlake (2001) and Moss and Townsend (2000) actually refer. From Table 3, it can be read that empirical studies have not always employed the relevant terminologies. First, typical GaWC researches are not simply able to measure a city’s “world city-ness” (Beaverstock et al., 1999, p. 446) or to go “beyond Friedmann’s world city hierarchy” (Derudder et al., 2003, p. 876). Second, a spatial analysis of a mergers and acquisitions (M&As) cannot be compared directly to the landscapes “pictured by Sassen and Taylor” (Rodríguez-Pose and Zademach, 2002, p. 1911). Geographies of M&As, shifting spatialities of corporate HQs, and changing patterns of FDI are not necessarily unimportant for Sassen, but these economic-geographical changes only enter her analysis insofar these fuel the necessity for highly complex and tailor-made services. Furthermore, these services are not necessarily produced on-site (Sassen, 2001a, p. xx). Third, it is unclear why Malecki’s (2002) Internet data seems to capture the geography of world cities, while they enable Townsend (2001, p. 4) “[t]o illustrate how global cities have fared in the rapid and massive deployment of Internet networks” (see IV.4).
Table 3: Employed and relevant terminologies in recent empirical studies of a transnational urban network .
A blurry discourse is, of course, not necessarily a sign of a sweeping conceptual conflation. For instance, despite favouring the term ‘world city’, GaWC-researches unambiguously refer to Sassen’s work on place and production in a global economy. Thus, there can be little doubt that GaWC-studies present an analysis of global cities8, and passing judgment on the basis of an erroneous terminology would therefore be outright excessive. However, in the next paragraphs, I aim to show that this fuzzy use of terminologies is merely a symptom of a more profound conceptual confusion. To this end, I begin by discussing a recent empirical study by Alderson and Beckfield (2004) in more detail.
IV.2. Comparing Results of Different Concepts
In their article, Alderson and Beckfield (2004, p. 814) address two very concrete questions. First, the authors seek to “determine which cities are in fact central to the MNE-generated city-system.” Second, having established such a ranking of cities in terms of network centrality, they “examine precisely what sort of ‘system’ these cities form.” The latter question involves searching out the predominant structure of the network. Possible answers include a simple linear hierarchy, a core-periphery structure, a structure exemplified by cohesive subgroups bounded by trading blocs, etc... To answer both questions, Alderson and Beckfield (2004) utilize data on headquarter and branch locations of the world’s 500 largest multinational firms for the year 2000. Based on this location matrix, they construct a 3692 x 3692 inter-city matrix that paints a detailed picture of an MNE-generated urban network.
The first research question is answered through an analysis of three measures of ‘point centrality’, whereby most attention is given to the so-called ‘outdegree centrality’. The latter indicator captures the number of ‘headquarter ties’ sent from a given city, which leads Alderson and Beckfield (2004, p. 822 and pp. 827-828) to state that this is an “unambiguous indicator of world city-ness.” After having computed this measure for all cities, Alderson and Beckfield (2004, pp. 828-829) assess whether the emerging ranking differs substantially from other world city rankings. One of these rankings is Beaverstock et al.’s (1999) Roster of World Cities, a study based on an inventory of the level of advanced producer services in cities. Alderson and Beckfield (2004, p. 829) report that there are “notable discrepancies” between both lists: only 46% of the cities featuring in the Beaverstock et al. (1999) ranking have a significant position in the ranking based on the ‘outdegree centrality’. Furthermore, this overlap is almost exclusively confined to the most connected cities in the network. The latter observation is no surprise, according to Alderson and Beckfield (2004, p. 829), since leading researchers such as Friedman and Sassen have argued “that cities such as London, New York, and Tokyo sit at the top of the world city system.” However, despite the comforting parallels at the apex, the authors equally mention some “surprises at the top” (p. 829). First, Tokyo surpasses London and New York in this ranking, although it “is typically viewed as being eclipsed by London and New York in power” (p. 829). Second, “Paris emerges as a city of the first rank” (p. 829), whereby it is noted that this is in broad agreement with Smith and Timberlake’s (2001) airline network analysis. Third, two prominent names do not appear in their list, i.e. Singapore and Miami. The absence of the latter two cities, it is claimed, may be due to their importance in “regional city-systems” (pp. 829-830), while there is a more overarching concern about the extent to which these findings “may be biased by the type of data we employ” (p. 829).
The rationale for Alderson and Beckfield’s (2004, pp. 825-826) second research question can be traced back to suggestions that the emergent transnational urban network cuts across the core/periphery-divides in the world-system. To ‘measure’ the overall structure of the network, the authors employ a wide range of sophisticated network-analytical tools, whereby the overarching conclusion is that “[t]he average rank of cities located in semiperipheral countries is lower than that of core cities, whereas that of cities located in peripheral countries is lower still” (Alderson and Beckfield, 2004, p. 844). This leads Alderson and Beckfield (2004, p. 844) to state that this result is not consistent with “Sassen’s vision of a world city system in the grips of substantial global restructuring. Rather than cutting across the hierarchy of states in the interstate system, the contemporary urban hierarchy appears to map onto it fairly well.”
Despite the many merits of Alderson and Beckfield’s (2004) network analysis, one can discern a number of problems due to the failure to distinguish between different concepts, which is in turn legitimized by an inadequate discourse in other studies. Recall that Beaverstock et al.’s (1999) study is essentially an inventory of global cities (i.e. transnational service centers), while Alderson and Beckfield (2004) themselves analyse a network of world cities (i.e. global power centers). The low overlap between both rankings is therefore not so much “biased by the type of data” (p. 829), but can/should be traced back to the observation that these data sources capture different concepts that may or may not converge empirically. Thus, the observation that cities such as São Paulo, Seoul and Mexico City rank fairly high in Beaverstock et al. (1999) and fairly low in Alderson and Beckfield (2004) is no surprise at all, it merely reveals that these ‘semi-peripheral’ cities are well-connected service centres without being (economic) power houses in the world-economy. Moreover, the clear-cut core-periphery structure of this MNE-generated urban network cannot contradict Sassen’s claims of a transnational urban network ‘in the grips of substantial global restructuring’, since her suggestion pertains to a network of global service centers . To assess Sassen’s proposition, one needs to apply Alderson and Beckfield’s (2004) network-analytical framework to a GaWC-like dataset. For one thing, the observation that São Paulo, Seoul and Mexico City rank fairly high in Beaverstock et al. (1999) and Derudder et al. (2003), but fairly low in Alderson and Beckfield (2004), is in fact broadly supportive for Sassen’s (1994, p. 4) claim that a network of global cities cuts across core/periphery divides. Furthermore, the fact that Paris is a well-connected city in the airline network (a measure of connectivity without a clear-cut conceptual background, see IV.4) can hardly ‘support’ the observation that Paris ranks higher as power center than it ranks as a service center. And finally, the ‘remarkable’ importance of Tokyo in an MNE-generated city-system is in fact by no means surprising; it only appears that way when this dominance is discussed in terms of another concept (i.e. global cities). The fact of the matter is that Tokyo’s dominance in corporate HQ’s is Sassen’s starting point to call for another approach to functional centrality in the global economy. Indeed, Sassen (2001a, p. 108; see also Godfrey and Zhou, 1999) outright admits that Tokyo is the leading city in terms of corporate HQs, and states that this can be traced back to the fact that “participation in the global economy for [Japanese multinational] firms still means going through a lot of government channels given a fairly regulated economy. Hence, location in Tokyo is crucial.” One can hardly claim that Tokyo’s remarkable dominance in a network of world cities contrasts with Sassen’s assessment in the context of a network of global cities, especially if this observed dominance is in fact Sassen’s motive to call for a different perspective.
IV.3. The Territorial Demarcation of Cities
Although Alderson & Beckfield (2004) base their network analyses on an inter-city matrix detailing the relations between 3692 ‘unique cities’, their original data source featured a total of 5303 locations across the globe. The initial dataset was collapsed because “suburbs and the near hinterland should in many instances be conceptualized as integral parts of the larger urbanized region” (p. 817). As a consequence, in cases in which cities are located within the ‘boundaries’ of a larger metropolitan area, the authors recoded them as the metropolitan area. The specifics of this recoding are not spelled out in detail, Alderson & Beckfield (2004, p. 820) restrict themselves to the remark that information on locations of suburbs from the U.S. National Geographic Society was supplemented with data from online sources such as MapQuest. Joining suburbs to metropolitan areas in this fashion reduced the number of ‘unique cities’ from 5303 to 3692.
However, the joining of suburbs and near hinterlands to ‘metropolitan areas’ does not go far enough for a study of world cities. Recall that world cities are conceived as polycentric urban regions, cf. Friedmann’s (1995) designation of Kansai Region, Randstad Holland and the Ruhr Area as world cities. This parallels Sassen (2001a, p. xxi) observation that ‘typical’ world city functions such as MNE headquarters tend to be less tied to a limited number of key cities than commonly assumed: countries with a well developed infrastructure beyond their leading centers offer multiple location options, and some MNEs have indeed relocated their headquarters to second-tier cities or even small towns. The headquarter location of major corporations such as Vodafone well beyond leading business centres in the world-economy is emblematic here. Vodafone’s headquarter is located in Newbury/Reading, about 50 miles from the city center of London. Although this headquarter is not located in one of the classic or newly emerging business districts of the central city, conceptually it clearly adds up to London’s control function in the global capitalist system. Thus, joining several locations into a single unit of analysis should move well beyond joining suburbs to central cities: a suitable transformation of such a MNE-location matrix involves joining a large number of locations (sometimes even major cities) into a single urban region.
The critical issue here is that the size of cities depends on the dynamic of contemporary urban transformations a researcher wishes to emphasize. If the emphasis is on global service centers, then merely joining suburbs may suffice. If the emphasis is on formal command and coordination in an era of global management, then cities need to be conceived as large scale urban regions9. By employing a loose morphological criterion, Alderson & Beckfield (2004) balefully suggest that towns such as Geel (Belgium), Arnhem (the Netherlands) and Evansville (USA) can be conceived as potential world cities, while the ‘traditional cities’ that now constitute Randstad Holland are assessed on their own terms rather than in the appropriate context of the wider urban region.
IV.4. The Poor Conceptual Basis of Infrastructure Analyses
In the previous paragraphs, I argued that the analytical merits of an inherently worthwhile analysis are downplayed because the results are interpreted in a different analytical context. This paragraph addresses a related example of this loose use of concepts: airline data, it is sometimes suggested, are somewhat serendipitously able to overcome the ambiguities in how we understand globalized urbanization. The overview in Table 3 already suggested that airline data are thought to be able to capture the spatiality of all specific concepts in a single analysis. Thus, it is suggested that a single analysis of the global airline network is able to assess the geography of important cities, large cities, world cities, and global cities. I began this list with the nonsensical term ‘important cities’, because some of the analyses have no conceptual background at all. Matsumoto (2004, p. 241), for instance, uses the overarching term “worldwide urban system,” and simply states that he intends to examine “international urban systems from the standpoint of international air traffic flows.” There is not a single reference to theoretical contributions, and Matsumoto’s ‘conceptual framework’ merely rests upon the commonplace remark that “large hub airport serving many destinations with frequent flights has the potential of exerting a major impact on adjacent urban areas” (p. 241).
Keeling (1995) and Rimmer (1998) aim to move beyond such straightforward assertion by making a closer analytical connection to theoretical researches. The authors thereby draw upon some conceptual insights for emphasizing the relevance of airline data. Keeling (1995, p. 116), for instance, provides 5 inter-related arguments as to why airline linkages are a suitable data source to assess a network of world cities:
In spite of these ‘arguments’, however, it remains unclear how these very general and commonsensical ideas may serve our empirical understanding of global urbanization: the fact that air transport is the preferred mode of inter-city movement for the transnational capitalist class, migrants, tourists, and high-value goods does not imply that information on such flows allows for an unproblematic assessment of world cities. The real analytical links are passed over in silence, and therefore a more thorough line of argumentation is needed.
The most systematic airline-based researches are the network analyses by Smith and Timberlake (2001, 2002, 2005; see also Shin and Timberlake, 2001). Smith and Timberlake have made use of refined datasets and network-analytical frameworks, but – more importantly for the present discussion – have equally tried to make such analytical connections to the theoretical literature. Indeed, Smith and Timberlake (1993, p. 197, see also 1995a,b) were among the first authors to note the potential ‘happy marriage’ between social network analysis and the study of a transnational urban network, and it is quite clear that this has profoundly influenced their ensuing airline analyses. Taken as a whole, Smith and Timberlake seem to favour Friedmann’s world city approach (cf. their multiple references to ‘power’), albeit that there are equally some references to Sassen’s global cities. For instance, while the “intra-urban links and flows” of airline networks can be used to assess “the contemporary global city network” (Smith and Timberlake, 2005, p. 76), it can be noted that their results
“indicate that there is a sharply defined hierarchy of dominance within a tier of the most important world cities, and this top tier has grown to include more cities over the last twelve years. It comprises the familiar cities identified by Sassen and Friedmann: New York, Tokyo, London, Paris, Frankfurt, and Los Angeles” (Smith and Timberlake, 2002, p. 139).
At the same time, Smith and Timberlake (2002, p. 139) warn us that “making too much of [the] analysis of airline passenger exchanges would be a mistake.” This is not just because there are myriad other ways in which the “world’s great cities are interlinked,” but also because there seem to be some generic interpretation problems with this particular data source (for a systematic overview, see Derudder and Witlox, 2005a,b). One of the most notable problems in this context is the observation that the connectivity of cities such as Frankfurt and Amsterdam cannot straightforwardly be traced back to a single, central location. Rather, these airports are in practice serving “an emergent form in the global urban hierarchy” (Smith and Timberlake, 2001, p. 1671). This “emergent form” is a city-region that consists of a set of major and lesser centres together with their hinterlands. Because of the broad territorial basis and inherently polycentric character of these city-regions, it would, according to Smith and Timberlake (2001), be misleading to conceive Frankfurt and Amsterdam as the ‘real’ units of analysis in their airline-based studies. Rather, it seems more fruitful to speak of the “Rhine-Main conurbation” (p. 1671) and the “Randstad conurbation (which also includes Rotterdam and The Hague)” (p. 1672). Similar remarks can be found in the airline analysis by Kunzmann (1998), who suggests that such an analysis pertains to ‘world city regions’. Both Kunzmann (1998) and Smith and Timberlake (2001) clearly rightly suggest that at least the classical hinterland conception remains implicated in the analysis of international airports, since the connectivity is a function of both the city and its surrounding urban field. Although this clearly reveals the inadequacy of this data source in the context of a global city analysis, it would be incorrect to ascertain that this data source therefore allows analysing a network of world cities. In the case of Amsterdam, for instance, even an extension of the unit of analysis to Randstad Holland may not do the job: Amsterdam Airport (Schiphol) is pretty much a national airport, so that the connectivity measured in airline data simply pertains to the territorial state as a whole rather than to its key city.
In sum, airline data are most certainly not able to assess all concepts in a single empirical framework. The observation that a data source reveals the “ familiar cities identified by Sassen and Friedmann” (Smith and Timberlake, 2002, p. 139) does not guarantee that these data capture analytically meaningful flows. The fact of the matter is that a look on a map of global airline connections tells us little on the specifics of global urbanization, especially when these connections refer to general flows to and from a territorial state as a whole. The basic reason for the observed lack of conceptual rigor in infrastructure-based studies can therefore be traced back to the weak analytical basis of this type of data. Indeed, in contrast to data on corporate organization, the relevance of infrastructure data appeals more to common sense than to a precise concept. As a consequence, t he employed terminologies in infrastructure network-based studies (see Table 3) are not so much reminiscent of a precise empirical specification as in Taylor (2001) and Alderson and Beckfield (2004), but merely an indistinct attempt to suggest a credible conceptual backdrop.
Based on an earlier overview of empirical studies, Beaverstock et al. (2000b, p. 126) argued that “the world cities literature is seriously unbalanced: it has a surfeit of interesting theoretical concepts for treating the nodes of the world city network, but these exist alongside a deficit in empirical concern for measuring relations between the nodes.” In the past few years there have been a number of attempts to rectify this situation. The studies in Table 1 therefore epitomize a laudable shift that has great merits in bringing empirical research in line with theoretical ideas on cities as nodes in a genuine network. However, at the same time, it is not unproblematic to subsume “interesting theoretical concepts” under the notion of a “world cities literature” in which one can discern a distinct conceptual path. Indeed, the whole idea of there being ‘important cities’ as nodes in a ‘transnational urban network’ can at best be seen as an analytically meaningless starting point for more precise conceptualizations (Markusen, 1999).
The observation that cities such as London, New York, Tokyo, and Paris, invariably feature at the apex of the various rosters of world cities, global cities, and global city-regions does not imply that these concepts feature the same set of ‘important cities’. Furthermore, there is no reason to assume that a data source that identifies these common sense names as highly connected nodes is capable to assess the spatiality of each of these concepts. Although there is indeed a general requirement for relational data, as Beaverstock et al. (2000b, p. 126) and Taylor (2004, p. 39) remind us, there is equally a specific requirement for different types of relational data for assessing different concepts. To put it in Markusen’s (1999) terms: the idea of a transnational urban network can connote but not denote, so that empirical studies can only affirm their relevance and analytical weight against a proper conceptual background. A lack of conceptual rigor may fuel the growth of chaotic conceptions, whereby data analyses risk being empiricist rather than empirical.
This conceptual confusion, I have argued at the outset of this paper, is not solely confined to recent empirical studies. It is part of a broader tendency that ascertains that the various approaches “are perhaps not quite as distinct as they may seem” (Hall, 2001, p. 61). Such a statement should not and cannot be dismissed right away. Indeed, it is of course possible to turn my approach on its head: why is it that, despite being distinct concepts, most of today’s leading global cities are also major world cities? Why is it that Beaverstock et al.’s (1999) and Derudder et al.’s (2003) rankings of global cities all in all map fairly well onto existing core/periphery patterns? These are important and pertinent questions, but the gist of my argument has been that such questions cannot be solved empirically; they need to be confronted theoretically. Parnreiter at al. (2005) and Brown et al. (2005) have recently undertaken such studies. Both papers propose to analyze the (as yet unidentified) ways in which the inherent spatial equality created by global commodity chains is facilitated by advanced servicing from a ‘nearby’ global city – Parnreiter et al. (2005, p. 1) aptly speak of a “ missing link between global commodity chains and global cities.” If meaningful regionalized links between (i) firms that are part of an MNE-structure and (ii) a ‘nearby’ producer service complex can be revealed, then we can make a start with addressing the parallels between world city and global city-formation. The main point here is that such an uncovering should proceed in the manner suggested by Parnreiter at al. (2005) and Brown et al. (2005), and not on the basis of some superficial parallels i n empirical rankings. Despite some significant recent advances in the empirical literature, there are still significant ambiguities in this body of research. For one thing, these ambiguities imply that further advances are needed in how we understand the phenomenon of global urbanization, both theoretically and empirically (see also Meyer, 2003 and Taylor, 2004).
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1. Admittedly, there are quite a few researchers that explicitly emphasize the importance of distinguishing between ‘global cities’ and ‘world cities’ (e.g. Smith, 2003a, p. 39; Short, 2004, pp. 2-3).
2. There are equally a limited number of empirical studies that cannot be subsumed under this bifurcation, such as Beaverstock et al. (2000a).
3. The latter is, of course, exactly what urban researchers have done in the last few decades. And with remarkable enthusiasm, it has to be said. In a recent paper, Taylor and Lang (2004, p. 952) were able to compile a list of 50 terms used to describe cities as nodes in border-crossing networks. The outstanding feature of this list is its sheer size, whereby finding 50 examples was “not a particularly onerous task.” There is, in other words, a plethora of concepts out there, and Taylor and Lang (2004, p. 953) rightfully remind us that there is “a threshold when additional concepts obfuscate rather than illuminate.” But there is, of course, equally a threshold at the other end of the spectrum where simply equating terms becomes problematic.
4. Sassen (2001a,b) equally engages with Allen Scott’s ‘global city-regions’ by stating that while global cities and global city-regions may “[a]s categories for analysis (…) share key propositions about economic globalization,” it is clear that they “overlap only partly in the features they each capture” (Sassen, 2001a, p. 351). As a consequence, they have “distinctive theoretical and empirical dimensions” (Sassen, 2001b, p. 70). Scott (2001a, p. 817), in turn, states that previous research on world and global cities provides the basic starting points for his investigation, but adds that he will seek to extend these concepts’ range of meaning “so as to incorporate the notion of the wider metropolitan region as an emerging political-economic unit with increasing autonomy of action on the national and world stages.”
5. This discussion is therefore not intended as an appraisal of these theoretical researches. Critical assessments of the concepts from a wide variety of theoretical positions can be found in Soja (2000, chapter 7); M.P. Smith (2001, chapter 3); Robinson (2002); and R.G. Smith (2003a,b).
6. There are earlier uses of this term, but Brenner (1998, p. 5) notes that these uses reflected the “territorialization of the urbanization process on the national scale: the cosmopolitan character of world cities was interpreted as an expression of their host states’ geopolitical power.”
7. Territorial states have, of course, been prime actors in the unfolding of this uneven development, but Mann (1986) has noted that the world-economy is radially rather than territorially managed. This means that the economic and political power of core territories is in fact spatially structured along well-defined routeways that link centres of control via available authorative and allocative resources. Hence, what is commonly labelled as ‘core’ in world-systems analysis does not necessarily consist of a series of ‘strong’ territorial states, but of a hierarchy of major and lesser centres (i.e. world cities) that thereupon diffuse their status and function over a wider area and at different scales (Dodgshon, 1999, p. 56).
8. The straightforward designation of GaWC studies as research into ‘global cities’ should, however, be nuanced. It can, for instance, be noted that the empirical rationale of most GaWC research start from a critique of Sassen’s global city concept for its bias towards a limited number of cities. Therefore their use of the term ‘world cities’, ‘globalizing cities’, and ‘cities in globalization’ may be considered as a deliberate move to enable a larger set of cities . Thus although Sassen’s process is used in GaWC studies, it can be said that they do try to bypass her concept of ‘global cities’. Furthermore, it is relevant that Friedmann (1986) mentions finance and ‘high level business services’, so there is some overlap between world cities and global cities in the original sources.
9. Thus, Godfrey and Zhou (1999) rightfully suggest that in the case of a world city analysis, the use of Consolidated Metropolitan Statistical Areas (CMSA)-like areas may be more appropriate. CMSA’s are geographic entitities designated by the US federal Office of Management and Budget for use by federal statistical agencies. An area becomes a CMSA if it qualifies as a metropolitan area, has a census population of one million or more, has component parts that qualify as primary metropolitan statistical areas based on official standards, and local opinion favors the designation. In the case of New York, for instance, the city is designated as the New York-Northern New Jersey-Long Island CMSA, and is constituted by counties situated in New York, New Jersey, Long Island and Pennsylvania .
Edited and posted on the web on 27th July 2005; last update 1st March 2006
Note: This Research Bulletin has been published in Urban Studies, 43 (11), (2006), 2027-2046