5Borge et al. (2012) examine different sources of hydropower revenue ranging from taxes and concession fees to business development funds in search for the impact of hydropower on productivity in Norwegian local governments. Even though this impact may add productivity and related concerns to regional differences discussions in Norway, we believe excluding hydropower will have negligible effect on our results within the construction of this piece, as our central aim is to focus on primary resource extraction and production rather than power generation, which is a secondary production process that utilizes renewable or nonrenewable resources as inputs. Therefore, we believe the impact of power generation from various resources on regional development could be investigated in a different context with a specific focus on spatial spillovers from the hydropower sector and others, which is beyond the scope of this study. Besides, we do not take into account local government revenues from natural resource activities; but consider investment, value-added and employment in these sectors instead.