In port cities there is a tendency to dislocate production activities in favour of logistic-productive dynamics. In addition, the transition from an industrial area model to a ‘logistics hinterland’ formula shifts attention to a territorial scale, focusing on spaces at the border between the port and city areas. Today, port–city borders are commonly perceived as barriers but they could be dynamic development thresholds. Existing port cities exhibit different states of coexistence at their port–city borders: sometimes they are forced situations originating from poor management, but they can also provide opportunities for mutual interaction and synergy. This paper compares port–city borders in Genoa and Rotterdam using interviews, relevant literature and mapping. Conclusions are drawn concerning the possibilities and potential for future port–city borders.