Global cities are still in many ways maritime cities (Dogan, 1988) or locate near seaports or sea-river ports (Vance, 1970). Port cities have also been vital centers of successive world systems throughout history (Braudel, 1979), from Tyr and Sidon in the Phoenician world to New York and Shanghai nowadays.
This communication aims to apply for the first time network analytical methods to maritime flows connecting cities of the world, over the long term (1890-2010). More likely were analyses of interurban connectivity through telecommunications, roads, highways, railways, which was extended later in the 1990s and after to airlines, multinational firms’ linkages, and the world-wide web.A global matrix of interurban vessel flows was elaborated for about 5,000 ports, 400,000 inter-port calls and 5,000 cities using data from the Geopolis, Populstats, World Gazetteer and Lloyd’s Shipping Index databases and the rigorous assignment of ports to both coastal and inland urban areas.
Preliminary results show that despite the observed decrease in the correlation between maritime flows and the urban hierarchy (10% loss between 1950 and 1990), the largest cities remain dominant in the network. These large cities (over 630) catch nearly 70% and 60% of worldwide flows and population, respectively. This dominance is also reflected in their higher network cen- trality, traffic share, and average (kilometric) length of flow linkages. Mapping largest maritime flows among world cities helps discovering hidden groups based on geographic or other proxim- ities, with a shift over time from a core-periphery to a more polycentric pattern. A typology of cities is also provided based on the evolution of their relative concentration index of population and traffic.
The latest research of PortEconomics member César Ducruet, along with Sylvain Cuyala and Ali El Hosni, contributes to question the ineluctable separation between ports and cities which dominated the literature, while offering new empirical evidence about the structure and dynamics of city-systems and spatial networks in general. All in all, this long-term historical perspective is a new empirical and methodological contribution to the theoretical debates on the intermingled evolution of cities, flows, networks, regionalisation, and globalisation.
Their study presented during the 2nd European Conference on Social Networks held 14-17 June in Paris, France and its presentation can be downloaded @ PortEconomics. Just follow the link.