Conceptualizing digital and physical connectivity: The position of European cities in Internet backbone and air traffic flows

'Digital' telecommunication flows and 'physical' corporeal flows provide researchers with comprehensive indicators of the economic interactions between cities. However, previous research drawing on telecommunication-based measures of inter-urban connectivity has been hampered by inadequate conceptualizations and data. This paper draws on this observation to devise a new approach for measuring inter-urban connectivity based on a city's insertion in Internet backbone networks. The straightforward example of air transport flows is thereby used to outline this approach. To investigate telecommunication and air passenger flows, use is made of European statistics on Internet eXchange Points and the MIDT airline database respectively. The approach is illustrated through a systematic comparison of the position of European cities in both types of networks. It is found that European cities assume largely similar hierarchical levels in terms of digital and physical information flows, albeit that the digital connectivity of centrally located European cities is often somewhat higher than that of peripheral cities with a similar levels of physical connectivity.