The geography of breakthrough invention in the United States over the 20th century

The geography of breakthrough invention in the U.S. – defined as the spatial distribution of the production of patents that are both novel and impactful – underwent three broad changes during the 20th century. At the start of the century, breakthrough invention was concentrated in populous metropolitan areas with high levels of local knowledge variety. By the 1930s, breakthroughs were created less frequently across the entire country and so their invention had a less distinct geography. The substantial creation of breakthroughs resumed in the 1960s, and while their invention was once again concentrated in major metropolitan areas with high knowledge variety, they frequently involved long-distance collaboration. In this article, I document these changes and propose a theory to interpret why they occurred. The theory emphasizes how changes in inventors' institutional and communication technology environments influence the geographical locations that are advantageous for breakthrough invention. In support of the model, I find that the disruptiveness of the regime of technological change, the knowledge intensity of breakthroughs, the distance-based frictions incurred by collaboration technologies, and the distance-based frictions incurred by knowledge-sourcing technologies help to predict the spatial distribution of breakthrough invention. To conclude the article, I discuss lessons that the 20th century's geography of breakthrough innovation provide for anticipating the geography of innovation in the 21st century, including in the years beyond COVID-19.