Interreg has been the European Union (EU) initiative to support territorial cooperation and integration across borders. 30 years of Interreg, though, have not changed the fact that different barriers persist at the inner borders of the EU, and that only a few cross-border territories have emerged as joint action spaces with in-depth political cooperation and people’s interaction. While it is consensus that cross-border economic flows are decisive for the development of functional and in the end institutionalized cross-border regions, regional econometric models demonstrate the persistence of border barriers within the EU, but also that the removal of these barriers greatly increases regional growth potential. In a research project focusing on the alignment of cross-border regional economic interests, cross-border networks between business and politics and cross-border policies in the Danish-German cross-border region Sønderjylland-Schleswig we have discovered issues on different communication codes between business and politics, lack of tangible cross-border development strategies and a lack of alignment of shortterm, time delimited Interreg project oriented operational programs to tangible, long-term strategies of cross-border regional economic development. EU territorial cohesion policies could be better aligned with long-term, cross-border economic strategies to create sustainable cross-border development. It will be important to rethink Interreg in a less project-oriented, but more strategy-oriented direction; focusing on flows and institutional settings promoting the development of flows by reducing cross-border barriers.