A surprisingly large amount of commentary today marks the beginning of the dot-com bubble of the late 1990s from either the Netscape Communications initial public offering of 1995 or Alan Greenspan's "irrational exuberance" speech of 1996. We believe that this is wrong: we see little sign that...

One of the most important representations of an urban spatial structure is its density. Indeed, an urban area is defined as a densely populated place with a sizeable number of inhabitants. Yet, despite the fact that the defining element of an urban area is its density, few scholars have...

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...

This review discusses frontier topics in economic geography as they relate to firms and agglomeration economies. We focus on areas where empirical research is scarce but possible. We first outline a conceptual framework for city formation that allows us to contemplate what empiricists might...

This paper studies the sources of agglomeration economies in cities. We begin by introducing a simple dynamic spatial equilibrium model that incorporates spillovers within and across industries, as well as city-size effects. The model generates a dynamic panel-data estimation equation. We...

This paper studies whether agents must agglomerate at a single location in a class of models of two-sided interaction. In these models there is an increasing returns effect that favors agglomeration, but also a crowding or market-impact effect that makes agents prefer to be in a market with...

Used properly, the term 'new e-conomy' is warranted. Since 1995, there has been a wave of innovation associated with both the production and use of information technology that has been translated into improved US economic performance. In particular, there has been a substantial acceleration in...

This paper studies the effect of top tax rates on inventors' international mobility since 1977. We put special emphasis on "superstar" inventors, those with the most abundant and most valuable patents. We use panel data on inventors from the United States and European Patent Offices to track...