The Geography of Knowledge Production: Connecting islands and ideas

This paper examines the importance of economic integration on the production of innovation. During the late 1980s and-90s, Shikoku and Honshu, Japan’s largest and fourth largest islands, were connected for the first time by three different bridges. This greatly reduced travel times compared to previous modes of transport such as ferry. We examine the impact of bridge connections on team formation and the production of knowledge, as measured by patent data. Using the geolocation of inventors before the opening of the bridges, we find that inventors located close to the bridges increased knowledge production more than inventors located farther away from the bridges. The treated inventors matched to more productive inventors at greater distances. Inventors on Shikoku were more likely to change their innovation teams and add co-inventors from Honshu while dismissing collaborators from Shikoku. The results are robust to instrumenting for the location of the bridges using the minimum bridge span distances between Shikoku and Honshu. We present a parsimonious economic framework that is largely consistent with the empirical evidence. Our results suggest that economic integration can have sizable effects on idea creation and innovation.