Combining agglomeration economies and endogenous growth without scale effects

Increasing returns to scale is essential to both spatial economics and macroeconomic growth. Spatial externalities imply external local increasing returns that generate an uneven spatial distribution of economic activity. While non-rival knowledge also implies increasing returns - in order to endogenise growth - this is not a spatial micro-foundation. Spatial theories of growth must be carefully specified to avoid unintended conclusions about the spatial economy and scale effects. This is demonstrated with a spatial endogenous growth model without scale effects that includes a spatial mechanism that facilitates agglomeration economies for innovation. In this class of models that combine spatial mechanisms with endogenous growth without scale effects, local increasing returns to scale imply that productivity, growth and interest rates are functions of the economy's spatial distribution, but not its scale.