This article discusses the creation of contemporary regional borders in the Western and Northern Lands, which were incorporated into Poland after the Second World War. Using the example of Żuławy and Powiśle, the author presents an anthropological analysis of the social, cultural, and administrative developments in the region, as well as the effect of those changes on the perception of these areas by their current inhabitants. Hence, she describes the strategies used to legitimise the borders of Żuławy and Powiśle by the local communities and institutions. The author discusses different approaches to the notion of regional borders, and their relation to historical, cultural, geographic and administrative borders. She further analyses the emergence of regional borderlands, centres, and peripheries. Data regarding the borders of Żuławy and Powiśle has been collected using mixed methods research. Both qualitative research methods (conceptual maps, targeted in-depth interviews conducted among leaders and representatives of institutions) and quantitative research methods (questionnaires conducted among the inhabitants) had been used.