We model spatial clusters of similar firms. Our model highlights how agglomerative forces lead to localized, individual connections among firms, while interaction costs generate a defined distance over which attraction forces operate. Overlapping firm interactions yield agglomeration clusters...

Global production sharing is determined by international cost differences and frictions related to the costs of unbundling stages spatially. The interaction between these forces depends on engineering details of the production process with two extremes being 'snakes' and 'spiders'. Snakes are...

The explosion of multinational activities in recent decades is rapidly transforming the global landscape of industrial production. But are the emerging clusters of multinational production the rule or the exception? What drives the offshore agglomeration of multinational firms in comparison to...

A Melitz-style model of monopolistic competition with heterogeneous firms is integrated into a simple New Economic Geography model to show that the standard assumption of identical firms is neither necessary nor innocuous. We show that re-locating to the big region is most attractive for the...

The growth of high-technology clusters in the United States suggests the presence of strong regional agglomeration effects that reflect proximity to universities or other research institutions. Using data on licensed patents from the University of California, Stanford University, and Columbia...

In recent empirical literature on spatial agglomeration, many papers find evidence consistent with location-specific externalities of some sort. Our willingness to accept evidence of agglomeration economies depends on how well key estimation problems have been addressed. Three issues are...

The degree of geographic concentration of individual manufacturing industries in the U.S. has declined only slightly in the last twenty years. At the same time, new plant births, plant expansions, contractions and closures have shifted large quantities of employment across plants, firms, and...

This paper discusses the prevalence of Silicon Valley-style localizations of individual manufacturing industries in the United States. Several models in which firms choose locations by throwing darts at a map are used to test whether the degree of localization is greater than would be expected...

When economic activity is concentrated over space or over time, it is more efficient. Most production occurs in geographic hot spots, and most production occurs between 9 and 12 in the morning and 1 to 5 in the afternoon on weekdays. The thick-market efficiencies that encourage the concentration...

The distribution of firms in space is far from uniform. Some locations host the most productive large firms, while others barely attract any. In this paper, I study the sorting of heterogeneous firms across locations and analyze policies designed to attract firms to particular regions...