Surname Diversity, Social Ties and Innovation

We study whether interactions between individuals with different skills, expertise and perspectives influenced innovation in U.S. counties from 1850 to 1940. We introduce and validate a new measure of social interactional diversity based on the distribution of surnames: lower surname diversity indicates more concentrated social interactions among like-minded people. Leveraging quasi-random variation in counties' surname compositions---stemming from the interplay between historical fluctuations in immigration and local factors that attract immigrants---we find that surname diversity increases both the quantity and quality of innovation. The results support the view that social interactions between diverse minds are key drivers of innovation