This working paper supersedes WP 12-22, WP 11-42, and WP 10-33. We employ a unique data set to examine the spatial clustering of private R&D labs, and, using patent citations data, we provide evidence of localized knowledge spillovers within these clusters. Jaffe, Trajtenberg, and Henderson...

Despite much theorizing about the role of geographic concentration of employment in knowledge spillovers, local densities' role in promoting innovations has largely been unexamined. More often, studies have considered the effects of city size variables on innovative activity, although the role...

In the U.S., metropolitan areas contain the largest concentrations of people and jobs. Despite some drawbacks, these so-called agglomeration economies also have benefits, such as the cost savings that result from being close to suppliers and workers. Spatial concentration is even more pronounced...