Does an open border necessarily contribute to a higher level of cross-border interactions in comparison to a stricter border regime, to intensification of cross-border contacts and bring social and economic benefits for border regions? Border location of a region often means that it belongs to the economic and social periphery of a country. Is an open border a tool to destroy the vicious circle of interdependence between border and peripheral location? The case of the boundary between Russia and Belarus offers a good opportunity for answering these questions. It is the only boundary in the post-Soviet space where customs and border control practice have virtually never been in place. Its regime and functions are determined by the policy of integration declared by the leadership of both countries. The paper is based on an analysis of statistical sources, 59 expert interviews and 320 structured interviews with local inhabitants collected during field studies in 19 border rayons (2008–2018). The conclusion is that processes of state-building in both countries and the separation of their economic and social space had a much stronger influence on borderlands than the openness of the boundary and the policy of integration. Most border rayons remain depressed.