Robert W. Helsley

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We examine how interaction choices depend on the interplay of social and physical distance, and show that agents who are more central in the social network, or are located closer to the geographic center of interaction, choose higher levels of interactions in equilibrium. As a result, the level of interactivity in the economy as a whole will rise with the(More)
It is well established that the thickness of local markets can enhance entrepreneurial activity (Vernon (1960)). It has been more recently established that because they carry out so many different tasks, a balance of skills may be beneficial to entrepreneurs (Lazear (2004, 2005)). This paper unifies these approaches to agglomeration and entrepreneurship.(More)
Cities are neither completely specialized nor completely diverse. However, the theoretical agglomeration literature has focused almost entirely on the polar cases of complete diversity and specialization. In order to give theoretical foundations to cluster analysis, this paper develops a model that can also generate the intermediate case of cities that(More)
Housing supply plays an important role in the Volatility of macroeconomic cycles and the speed with wl-iich house prices respond to changes in demand, yet it is understudied in the current literature. In this paper we present and estimate a new model of the supply of residential construction that is consistent with the theoretical treatment of land(More)
Rushes are a fundamental characteristic of the growth of many industries and cities. To explain these rushes, and better understand the mechanisms of growth, this paper develops a model centered on a new tradeoff between fundamentals and opportunities. Early growth in industries and cities depend critically on the opportunities they provide; whether from(More)
Despite wide recognition of their significant role in explaining sustained growth and economic development, uncompensated knowledge spillovers have not yet been fully modeled with a microeconomic foundation. The main purpose of this paper is to illustrate the exchange of knowledge as well as its consequences on agglomerative activity in a(More)
We present a theory of spatial development. Manufacturing and services …rms located in a continuous geographic area choose each period how much to innovate. Firms trade subject to transport costs and technology di¤uses spatially. We apply the model to study the evolution of the U.S. economy in the last half-century and …nd that it can generate the reduction(More)
Traditional models of systems of cities focus almost entirely on the polar cases of completely diverse and completely specialized cities. The former are shown to be the product of urbanization economies, and the latter of localization economies. This paper specifies models that can also generate the intermediate case of cities that feature the(More)
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