The Geography of Unconventional Innovation

Abstract

Using a newly assembled dataset of U.S. patents, we show that overall innovation activity is less concentrated in high-density urban areas than commonly believed, but inventions based on atypical combinations of knowledge are indeed more prevalent in high-density cities. To interpret this relation, we propose that informal interactions in densely populated areas help knowledge flows between distant fields, but are less relevant for flows between close fields. We build a model of innovation in a spatial economy that endogenously generates the pattern observed in the data: specialized clusters emerge in low-density areas, whereas high-density cities diversify and produce unconventional ideas.