We argue that “buying local” does not necessarily reduce transport‐related greenhouse gas emissions, even if production technologies and yields are homogeneous in space. We develop a partial‐equilibrium model of rural‐urban systems where the spatial distribution of food production within and between regions is endogenous. We exhibit cases where locating some food production in the least‐urbanized regions results in lower emissions and higher welfare than if all regions are self‐sufficient. The optimal spatial allocation of food production does not exclude the possibility that some regions should be self‐sufficient, provided that their urban population sizes are neither too large nor too small.