Cross-border regional economic ties in the EU have been the subject of numerous studies across various academic fields. A special dose of attention, however, has been paid to the ties between the EU border regions. This is no doubt related to the intensification of European integration, in particular at the regional level. One source of particular impact on border regions is the economy of the common market. Surprisingly enough, this economy has not found its proper reflection in the research on border regions and their problems in the light of the broadly defined European regional studies. As a consequence, it is necessary to carry out an in-depth analysis of the literature on cross-border cooperation and economic integration in order to capture the impact of the single market on cross-border relations. The aim of this paper, therefore, is to analyze the economic determinants of cross-border economic ties between the EU regions. To this end, the text begins with an overview of (1) the key characteristics of the common market, followed by (2) the impact of market economics on the regional ties, with particular emphasis on the border regions. The problem has been illustrated on the basis of the Polish-German borderland. The conducted examinations indicate that the economic ties between border regions vary in intensity. At the same time, the vicinity of the border is often insufficient as a factor ensuring a high degree of intensity in the movement of production factors or business relations across the border. It is market mechanisms rather than the location on the border that comprise the primary determinant in this regard. The primary focus of this study is the movement of production factors. The methodology of this text has been based primarily on the analysis of the subject literature on the notions of market economics, optimum currency area, and the broadly defined European regional studies.