Measuring the World City Network: New Results and Developments

The Interlocking Network Model

Networks are relatively easy to understand. They usually consist of two layers, the net level and the node level. For instance, in a social network analysis of a gang, members are nodes, the gang is the net level and relations between the nodes (members) define the nature of the network. Formal city government associations work in this way with the cities (members) as nodes, the city association represents the net level, and the formal relations between members within the association define the network. Such networks can be an important component of global governance but this is not how cities operate as key components of the global economy. In the latter, it is advanced producer service firms that are the network makers; they create the world city network through their everyday practices linking offices across the world. This defines a different type of network, an interlocking network (Knoke & Kuklinski, 1982).

An interlocking network is unusual in having three layers. In the case of the world city network there is the net level of the global economy, the node level of cities, and an additional sub-nodal level of service firms. The latter are not just an additional level, they define the critical level: this is where the agents of network formation are found. In the global economy, it is firms who are the network makers not the cities themselves. Thus for studying the world city network it is service firms that are investigated in order to understand the city network as the outcome. In other words, it is through studying the locational strategies of firms that it is possible to describe and analyse the world city network: firms are the object of the research, cities are the subject of the research.