Dense Enough To Be Brilliant: Patents, Urbanization, and Transportation in Nineteenth Century America

This paper explores the geographical distribution of patenting in the nineteenth century United States, as it evolves in response to improvements in access to transportation. I revisit the Sokoloff (1988) hypothesis that increasing market access, caused by the spread of transportation infrastructure, led to an acceleration of innovation. I find that twenty years after the arrival of the railroad in a county, the number of patents per capita has doubled. Using cardinal detection lines from the most important ports in 1826 as an instrumental variable suggests that 30-70% of the increase in patenting between 1850 and 1860 was caused by the spread of the railroad in this period, and 15-30% of the increase between 1850 and 1870. These results are driven by the area of a county that is close enough make a round trip to transportation with in a day, and not by area further away. A 1% increase in the area of the county that is within 1.5 miles of some form of transport corresponds to a to a 1.5% increase in patenting. These results are robust to controls for urbanization. Much of the effect comes from patenting in counties that had not previously patented, suggesting that new access to existing markets spurs development and leads to integration into broader markets for innovation.