This paper presents a new methodology to measure border effects from a different perspective with respect to the standard gravitational approach. The methodology proposed measures supply-side border effects by identifying two types of limits produced by the border to the productive system: inefficiency in exploiting local resources (efficiency needs) and scarce endowment of resources (endowment needs), the former calling for intervention on resource governance, the latter requiring new investment. The methodology, applied to the European Union's Cross Border Cooperation Program regions, suggests a stronger presence of efficiency needs with respect to endowment ones.