We study the effect of high speed trains on the spatial distribution of innovation, research collaboration, firms’ organization and inventors’ mobility. We use French micro data of firms, matched employer-employee information and patent data. We construct a dataset of city-to-city travel time by train in France covering the period 1980-2020. We exploit the rollout of high speed trains to provide causal evidence. Preliminary results show that a decrease in travel time led to an increase in collaboration between inventors located in different departments.

We study the impact of the expansion of US railroads in the late 19th century on patenting activity. We combine historical data on patents and the railroad network. We find that once a county is better connected to other counties with high patenting activity, patenting in that county goes up, controlling for increased market access. This effect is stronger if innovation in connected counties is complementary, calculated as the technological proximity in an input-output matrix of patent citations. We derive a model based on the framework in Eaton and Kortum (2002) that rationalizes these findings.

This paper studies empirically the impact of foreign demand on domestic innovation. I use multi-country multi-product data on patents and international trade for the period 1995-2010. I construct a measure of foreign demand for each product and country, and relate it to changes in patenting within that country. The results are in line with the theoretical predictions of Aghion et al. (2017) where initially more productive exporters increase the innovation effort as response to an exogenous increase in demand.