In the recent years, with the impact of globalization and the increasing social, economic and political relations, marginalized border regions have transformed into spaces of social, economic and political interaction. This changing character of borders provides different dynamics for social, economic and spatial relations of both sides. This study aims to discover the relational border space by analysing socio-spatial network structures caused by social and spatial interactions in the west and east borderlands in Turkey. The concept of relational border space perceives and analyses the border not only as a physical passage but also as a space of geopolitical, socio-cultural and economic interactions. Here, border transforms into a concept of a region, including all flows passing through the borderline, thus forming the base of the socio-spatial network structure. Within this context, this paper first reviews recent studies in conceptual bases on relational geography and socio-spatial networks and tries to understand how economic, social and spatial flows crossing borders affect the level of interaction, thus the permeability of the border. Then, it studies socio-spatial network structures in Turkey's west and east borders considering the border space and settlements.