This paper estimates the agglomeration benefits that arise from vertical linkages between firms. We identify the agglomeration benefits off the spatial variation in firms' nominal wages. Using unusually detailed intermediate input data, we take account of the location of input suppliers to estimate cost linkages; and the location of demand from final consumers and other firms to estimate demand linkages. The results show that the externalities that arise from demand and cost linkages are quantitatively important and highly localized. An increase in either cost or demand linkages from the 10th to the 90th percentile increases wages by more than 20%.