The main goal of this paper is to identify mutual influences between the specialization of traffics passing through seaports and the socio-economic characteristics of their surrounding regions. While the contemporary era is marked by the fading spatial fix of value chains as notably seen in the dereliction of port's local linkages, a systematic and comparative empirical analysis remains lacking. One main reason is the absence of internationally harmonized data on the precise spatial distribution of port-related hinterland flows as well as inadequacies between the volume and the value of freight. This research proposes to overcome such difficulties based on a common set of 21 traffic and socio-economic indicators covering 189 port regions in Europe, Japan, and the United States. Main results underline invariants as well as local specificities in the functional and spatial affinity between certain traffics and certain types of regions. While large urban and financial centres tend to polarize most valued, diversified, and weighty traffics, rural regions generally concentrate agricultural goods and minerals, and industrial regions concentrate combustibles and metals. Beyond the simple reflection of local demand, such results confirm the path-dependency of the association between material flows and regional economic development. A typology of port regions is proposed in order to map the distribution of port regions and to zoom on specific local conditions.