Historians observe that printing diffused from Mainz in “concentric circles” (Barbier 2006). Distance from Mainz was significantly associated with early adoption of the printing press, but neither with city growth before the diffusion of printing nor with other observable determinants of subsequent growth. The geographic pattern of diffusion thus arguably allows us to identify exogenous variation in adoption. Exploiting distance from Mainz as an instrument for adoption, I find large and significant estimates of the relationship between the adoption of the printing press and city growth. I find a 60 percentage point growth advantage between 1500-1600.Here's an example of how:
Cities that adopted print media benefitted from positive spillovers in human capital accumulation and technological change broadly defined. These spillovers exerted an upward pressure on the returns to labour, made cities culturally dynamic, and attracted migrants.