This paper critically considers the conceptualization of the ‘region’ in regional economic development. It utilizes the Durban Aerotropolis in KwaZulu-Natal, South Africa as a case of reference through which the conceptualization and underpinnings of ‘region’ associated with economic development are understood. This exercise is prompted by the nomenclatural shifts in local government from local economic development to regional economic development which is causing shifts in approaches to the implementation of economic development projects. The findings presented in this paper show that in the conceptualisation of the region in the instance of the Durban Aerotropolis, understanding the function, form and scale of a regional economic development project becomes pertinent to the social construction of the region with consequences for the project focus and implementation. In the discussion, function is examined as the purpose of a regional economic development project, form refers to the kind of economic development mechanism or strategy which could assist in fulfilling that purpose and scale speaks to the extent, reach and magnitude of the project, without which the implications are challenging practical enactment or implementation of regional economic development projects. The social constructions of region outlined in this paper thereby attest to the multiplicity of definitions which are typically based on the context in which the concept is being used and thus shows the ‘region’ inherent in regional economic development as produced through, and for, an assemblage of economic activity in space. From this we understand the region in regional economic development to be a social construct which presents itself as an assemblage of economic activity in space. Although we understand regions as spatially contingent, the theoretical and empirical conceptualisation of regions within regional economic development planning, policy–making and practice must draw on the specifics of contextuality to ensure its utility to economic development.