This paper generalizes and extends the labor market search and matching model of Berliant, Reed, and Wang (2006). In this model, the density of cities is determined endogenously, but the matching process becomes more efficient as density increases. As a result, workers become more selective in...

We geocode a data set of patents and their citation counts, including citations from abroad. This allows us to examine both the quantity and quality of local inventions. We also refine our data on local academic R&D to explore effectsnfrom different fields of science and sources of R&D funding....

Economists, beginning with Alfred Marshall, have studied the significance of cities in the production and exploitation of information externalities that, today, we call knowledge spillovers. This paper presents robust evidence of those effects. We show that patent intensity - the per capita...

This chapter documents instances from past centuries where inventors freely shared knowledge of their innovations with other inventors. It is widely believed that such knowledge sharing is a recent development, as in Open Source Software. Our survey shows, instead, that innovators have long...