Other Topics Papers

Other Topics Papers


Transitioning to driverless cars

Cityscape: A Journal of Policy Development and Research, 2016, 18 (3), 193-196
Agglomeration effects in Colombia  Abstract 
Journal of Regional Science, 2015, 56 (2), 210-238

I estimate an elasticity of wages with respect to city population of about 5 percent for Colombian cities. This finding is robust to a number of econometric concerns. The second main finding is a negative effect of market access on wages. Third main finding regards stronger agglomeration effects in the informal sector. In turn, this explains a range of other negative findings, including only weak evidence in favor of human capital externalities, no evidence of a complementarity between cities and skills, and an absence of learning effects. I do not find measurable effects of roads or amenities on wages either.
The urbanization and development puzzle  Abstract 
The Buzz in Cities: New Economic Thinking

This chapter argues for more academic investments in understanding urbanization in developing countries. It advocates for micro-based research that neither falls into the trap of poorly identified macro studies nor gets too narrow and loses sight of the big picture.
Agglomeration and jobs  Abstract 
Handbook of Regional Science Manfred Fisher and Peter Nijkamp (ed), 2014, Springer-Verlag, Berlin, 631-648.

This chapter discusses the literature on agglomeration economies from the perspective of jobs and job dynamics. It provides a partial review of the empirical evidence on agglomeration externalities; the functionality of cities; the dynamic relationship between cities, jobs, and firms; and the linkages between cities. We provide the following conclusions. First, agglomeration effects are quantitatively important and pervasive. Second, the productive advantage of large cities is constantly eroded and needs to be sustained by new job creations and innovations. Third, this process of creative destruction in cities, which is fundamental for aggregate growth, is determined by the characteristics of urban systems and broader institutional features. We highlight important differences between developing countries and more advanced economies. A major challenge for developing countries is the transformation of their urban systems into drivers of economic growth.
The growth of metropolitan areas in the United States
Chapter in Revitalizing American Cities, 2013, University of Pennsylvania Press (edited by Susan Wachter and Kimberly Zeuli), 26-44
Innovation in cities: classical and random urban growth models
Chapter in Handbook of Research on Innovation and Entrepreneurship, 2011 Edward Elgar, (edited by David Audretsch, Oliver Falck, and Stephan Heblich), 137-149.
Urban growth: Trends vs. noise
Theoretical and Practical Aspects of Urban and Regional Development, 2009, edited by T. Markowski and M. Turala, Polish Academy of Sciences, 23-38
Family types and the persistence of regional disparities in Europe
(with Andrés Rodríguez-Pose and Richard Sandall)  Abstract 
Economic Geography, 85(1), 2009, 23-47

This article examines the association between one of the most basic institutional forms, the family, and a series of demographic, educational, social, and economic indicators across regions in Europe. Using Emmanuel Todd’s classification of medieval European family systems, we identify potential links between family types and regional disparities in household size, educational attainment, social capital, labor participation, sectoral structure, wealth, and inequality. The results indicate that medieval family structures seem to have influenced European regional disparities in virtually every indicator that we considered. That these links remain, despite the influence of the modern state and population migration, suggests that such structures are either extremely resilient or in the past were internalized within other social and economic institutions as they developed.
Are cities engines of growth and prosperity for developing countries?
Urbanization and Growth, 2008, M. Spence P. C. Annez, and R. M. Buckley (eds), Commission on Growth and Development, Washington DC, pp. 67-114.
Spatial economics  Abstract 
Entry for the New Palgrave Dictionary of Economics (Second edition), 2008

This article provides a general overview of spatial economics, which covers location theory, spatial competition, and regional and urban economics. After a brief review of the main theoretical traditions, the fundamental role of non-convexities and imperfect competition is highlighted. The main challenges faced by theoretical and empirical research are also discussed, followed by a broader discussion of the relationship between this field of research and other sub-fields of economics and other disciplines.
The insatiable demand for land: Urban change and land (re-) development  Abstract 
Chapter in OECD/ECMT Roundtable 137: Transport, Urban Form and Economic Growth, OECD, Paris, 2008

Containing sprawl is a major preoccupation of many urban planners, who view sprawl as responsible for driving up environmental costs and congestion. Nevertheless, many economists see benefits to sprawl, allowing households access to larger and cheaper properties. This Round Table examines the costs and benefits of sprawl, shedding light on the linkages between urban form and economic growth, and explored the tradeoffs involved in trying to contain sprawl. Discussions were based on papers prepared by Elizabeth Deakin (UC Berkeley), Matthew Kahn (Tufts University), Gilles Duranton (University of Toronto) and David Banister (University College London).
Human capital externalities in cities: Identification and policy issues  Abstract 
Chapter in A Companion to Urban Economics, edited by Arnott and McMillen, 2006, Blackwell

This chapter analyses a few key issues pertaining to human capital externalities in cities. It shows the difficulties of properly identifying such externalities and explores the implications of such externalities for policy prescriptions.
Agglomeration and growth, a dialogue between economists and geographers
(with Michael Storper)  Abstract 
Journal of Economic Geography, 2006, 6(1), 1-7

This special issue contains papers by both economists and geographers on agglomeration and growth. In this introduction, we first provide a brief sketch of recent developments in the interaction between economists and geographers. We then propose some contextual background to make it easier for geographers to approach the economics papers of this issue and conversely. Finally, specific areas of overlapping interests to the two disciplines are also highlighted.
When economists and geographers collide, or the tale of the lions and the butterflies
(with Andrés Rodríguez-Pose)
Environment and Planning A, 2005, 37(10), 1695-1705
Recent development in regional and urban economics: Introduction
(with Paul Cheshire)  Abstract 
in Recent Advances in Regional and Urban Economics, Edward Elgar, 2004, edited by P. Cheshire and G. Duranton

In this collection, Paul Cheshire and Gilles Duranton have brought together the most significant contributions to regional and urban economics since 1990. The volume presents papers on theoretical and empirical analyses of city structure and systems of cities. It places particular emphasis on the empirics of agglomeration and regional growth with a special section on the new economic geography and includes key policy-oriented contributions. The editors have written an new introduction which offers a comprehensive overview of the subject.
A comparison between economic systems with an application to transition
(joint with T. Haniotis)  Abstract 
Journal of Public Economics 2004, 88 (9-10), 2125-2157

This paper develops a general equilibrium theory of endogenous firm and class formation under non-contractibility with heterogeneous individuals. A collectivist economy, a private-ownership economy, and a mixed economy are compared on the basis of identical economic fundamentals (methodological symmetry). Each economic system generates specific inefficiencies so that none dominates the others in general. The main trade-off is between the welfare loss associated with risk-taking in the private-ownership economy and the informational problems in the collectivist economy. We then use this framework to study the political economy of transition between economic systems and provide detailed welfare results.
The economics of production systems: Segmentation and skill-biased change  Abstract 
European Economic Review, 2004, 48 (2), 307-336

In this paper, the concept of production systems is introduced. I assume a standard thick-market externality together with the idea that higher quality goods also require higher skills from workers. Firms face a trade-off between low-quality goods with low skill-requirements for which the potentially abundant labour force generates strong thick-market externalities and higher quality goods with higher skill-requirements. In equilibrium, the economy is partitioned into production systems, i.e., clusters of firms producing the same quality. The distribution of skills determines the boundaries of the production systems, which in turn determine the wages. In this framework an increase in the supply of skilled workers can induce first higher wages for all workers and then higher wages for the skilled but lower wages for the unskilled. This is consistent with the late 20th century evolution of the US labour market.
The evolution of the U.K. north-south divide: Should we mind the gap?
(with Vassilis Monastiriotis)
European Investment Bank Papers 2001, 6(2), 42-57
Endogenous labor supply, growth and overlapping generations  Abstract 
Journal of Economic Behavior and Organization, 2001, 44 (3), 295-314

This paper explores a simple model of endogenous growth in an overlapping generations framework when labor supply is made endogenous. The following results are obtained: If leisure and consumption are substitutes, the economy can experience multiple equilibrium paths (including high growth and high labor supply or no growth and low labor supply). If the demand for leisure is inelastic, then the economy enjoys steady growth as in standard models. If leisure and consumption are complements, then production remains bounded, although endogenous growth is possible and socially desirable.
Cumulative investment and spillovers in the formation of technological landscapes  Abstract 
Journal of Industrial Economics, 2000, 48 (2), 205-213

In this paper, the evolution of product differentiation in industries is modeled as the result of a cumulative cost-reduction process subject to spillovers in a differentiated oligopoly. Our results suggest that the long-run outcome is dependent on the intensity of spillovers and the shape of their diffusion function. With weak spillovers, firms dig their niche over time, differentiation remains important and cost-reduction keeps going. By contrast, if spillovers are strong and have a concave diffusion function, firms gradually use more similar technologies. This standardization process involves less and less investment. For spillovers of intermediate strength, complex technological landscapes may arise.
Growth and imperfect competition on factor markets: Increasing returns and distribution  Abstract 
European Economic Review, 2000, 44 (2), 255-280

Although seldom modeled outside the monopolistic competition framework, market incompleteness and imperfect competition are central to the new growth theories. We propose here a strategic model of imperfect competition with endogenous growth and endogenous market structure where we focus on labor market issues. For growth to be possible, we assume increasing returns at the firm level. Due to heterogeneity on the labor market, the market structure is not degenerate. Then, because of increasing returns, short-run efficiency is maximized under monopoly and free entry implies too many firms in the market. However, in the long run competition can generate growth through a distribution effect, whereas a monopoly leads to a zero-growth steady state. Thus, there is a trade-off between static and dynamic efficiency. This trade-off implies the existence of a growth-maximizing degree of competition in our economy.
Trade, wage inequalities and disparities between countries: The technology connection  Abstract 
Growth and Change, 1999, 30 (4), 455-478

This paper takes seriously the idea that international trade has played an important role in explaining both some convergence between developed economies as well as rising inequalities at the personal level. Previous studies used traditional trade theory as a reference framework. The empirical consensus is now that differences in factor endowment explain at best a small fraction of rising wage inequalities. This argument, by contrast, builds on labor specialization and increasing returns. Deeper economic integration allows trade in differentiated intermediate goods and primary tasks, thus transforming local increasing returns into global increasing returns. This pushes towards geographical equalization. At the same time, deeper integration also increases the size of the pool of available skilled workers. This may lead them to a‘technological secession’as it makes more skill-demanding technologies more profitable. Technological secession in turn fosters wage inequalities at the personal level.
Agricultural productivity, trade, and industrialization  Abstract 
Oxford Economic Papers, 1998, 50 (2), 220-236

Traditional development economics states that industrialisation must be positively correlated with agricultural development as in the American and many European cases. However, some recent industrialisation experiences suggests a negative link which can be supported by a simple Ricardian argument Yet this argument is not consistent with the agricultural ‘leap forward’ that often occurred before industrialisation took place. Here, we develop a model in which, for a closed economy, industrialisation follows rising agricultural productivity. For a small open economy, multiple equilibria are possible and industrialisation tends to be associated with low agricultural productivity, but is triggered by sudden changes in it.
Comments on urban diversity and fiscal decentralization  Abstract 
Regional Science and Urban Economics, 1997, 27 (3), 801-806

In a recent and interesting paper published in this journal (Vol. 21, 1991, pp. 491–509), Henderson and Abdel-Rahman (HAR in what follows) study the consequences of a taste for diversity in a system of specialized cities. They show that the equilibrium city size is too big at the unregulated market equilibrium. Moreover, the decentralization of the first-best according to HAR is more demanding than in standard Tiebout models (they argue that autonomous local governments able to levy lump-sum taxes are needed). I argue on the contrary that under local public ownership of the land, the first-best is reached when the firms are able to control their wages. With absentee landowners, equilibrium city size is too small at the unregulated market equilibrium.

Urban Economics

Published Papers Urban Economics


Agglomeration effects in Colombia
  Abstract  
Journal of Regional Science, 56(2), 210-238

I estimate an elasticity of wages with respect to city population of about 5% for Colombian cities. This finding is robust to a number of econometric concerns. The second main finding is a negative effect of market access on wages. Third main finding regards stronger agglomeration effects in the informal sector. This third finding provides an explanation for a range of other negative findings, including only weak evidence in favour of human capital externalities, no evidence of a complementarity between cities and skills, and an absence of stronger agglomeration effects for older workers as would be predicted by the existence of learning effects. I do not find measurable effects of roads or amenities on wages either.

The logic of agglomeration
[published version]
(with William R. Kerr)  Abstract 
New Oxford Handbook of Economic Geography, Gordon L. Clark, Maryann Feldman, Meric Gertler and Dariusz Wojcik, (eds), Oxford University Press, Oxford

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 study when using firm-level data to compare the functioning of cities and industries with each other. We then examine a second model of the internal structure of a cluster to examine possibilities with firm level data for better exposing the internal operations of clusters. An overwhelming theme of our review is the vast scope for enhancements of our picture of agglomeration with the new data that are emerging.

Determinants of city growth in Colombia
  Abstract  
Papers in Regional Science, 95(1), 101-132

I develop an integrated approach to examine the drivers of population growth in Colombian cities between 1993 and 2010. Fertility plays an important role. Much of the higher growth of some Colombian cities can also be associated with higher wages. In turn, this wage advantage of some cities can be, in part, traced back to city education and industry shocks. I also find that roads matter but obtained mixed evidence about the role of urban amenities and no evidence regarding measures of urban costs and other drivers of urban growth that have been commonly considered by past literature. Some determinants of long-run city growth are also explored.

A proposal to delineate metropolitan areas in Colombia
 Abstract 
Economia & Desarrollo, 75(0), 169-210

This chapter first discusses the necessity of defining metropolitan areas and current practice in several countries. It argues for the use of a simple algorithm that exploits cross-municipality commuting patterns. Municipalities are aggregated iteratively provided they send a share of their commuters above a given threshold to the rest of a metropolitan area. This algorithm is implemented on Colombian data and its robustness is assessed. Finally, the properties of the resulting spatial labour market networks are explored.

Roads and trade in Colombia
 Abstract 
Economics of Transportation, 4(1), 16-36

I estimate the effect of major roads within and between cities on the level and composition of trade for Colombian cities. I confirm that road distance between cities is a major impediment to trade. In addition, major roads within cities have a large effect on a city׳s exports and imports with an elasticity of approximately 0.20 estimated with ols and up to 0.50 with iv. If anything, the effects are stronger for the value than for the weight of exports. I interpret these results as city roads shifting economic activity in cities towards the production of tradable and somewhat lighter goods.


Urban land use

(with Diego Puga)  Abstract 

Handbook of Regional and Urban Economics, volume 5A, 467-560

We provide an integrated treatment of the theoretical literature on urban land use inspired by the monocentric model, including extensions that deal with multiple endogenous business centers, various dimensions of heterogeneity, and durable housing. After presenting the theory and distilling its key empirical implications, we critically review the empirical literature on differences in prices and development across urban locations, patterns of location choices of heterogeneous households in cities, sprawl and residential decentralization, and employment decentralization.


Growing through cities in developing countries

 Abstract 

World Bank Research Observer, 2015, 30(1), 39-73

This paper examines the effects of urbanization on development and growth. It begins with a labor market perspective and emphasizes the importance of agglomeration economies, both static and dynamic. It then argues that more productive jobs in cities do not exist in a void and underscores the importance of job and firm dynamics. In turn, these dynamics are shaped by the broader characteristics of urban systems. A number of conclusions are drawn. First, agglomeration effects are quantitatively important and pervasive. Second, the productive advantage of large cities is constantly eroded and must be sustained by new job creation and innovation. Third, this process of creative destruction in cities, which is fundamental for aggregate growth, is determined in part by the characteristics of urban systems and broader institutional features. The paper highlights important differences between developing countries and more advanced economies. A major challenge for developing countries is to reinforce the role of their urban systems as drivers of economic growth.


The growth of cities

(with Diego Puga)  Abstract 

Handbook of Economic Growth, volume II, Philippe Aghion and Steven Durlauf (eds), Elsevier, 2014, 781-853, Amsterdam.

Why do cities grow in population, surface area, and income per person? Which cities grow faster and why? To these questions, the urban growth literature has offered a variety of answers. Within an integrated framework, this chapter reviews key theories with implications for urban growth. It then relates these theories to empirical evidence on the main drivers of city growth, drawn primarily from the United States and other developed countries. Consistent with the monocentric city model, fewer roads and restrictions on housing supply hinder urban growth. The fact that housing is durable also has important effects on the evolution of cities. In recent decades, cities with better amenities have grown faster. Agglomeration economies and human capital are also important drivers of city growth. Although more human capital, smaller firms, and a greater diversity in production foster urban growth, the exact channels through which those effects percolate are not clearly identified. Finally, shocks also determine the fate of cities. Structural changes affecting the broader economy have left a big footprint on the urban landscape. Small city-specific shocks also appear to matter, consistent with the recent wave of random growth models.


Productive cities: Sorting, selection, and agglomeration

(with Kristian Behrens and Frédéric Robert-Nicoud)  Abstract 

Journal of Political Economy, 2014, 122(3), 507-553

Large cities produce more output per capita than small cities. This may occur because more talented individuals sort into large cities, because large cities select more productive entrepreneurs and firms, or because of agglomeration economies. We develop a model of systemsof cities that combines all three elements and suggests interesting complementarities between them. The model can replicate stylised facts about sorting, agglomeration, and selection in cities. It can also generate Zipf’s law for cities. Finally, it provides a useful framework within which to reinterpret existing empirical evidence.


Roads and trade: Evidence from the U.S.

(with Peter Morrow and Matthew Turner)  Abstract 

Review of Economic Studies, 2014, 81(2), 681-724

We estimate the effects of interstate highways on the level and composition of trade for us cities. Highways within cities have a large effect on the weight of city exports with an elasticity of approximately 0.5. There is no discernible effect of highways on the total value of exports. Consistent with this, we find that cities with more highways specialize in sectors producing heavy goods.


Marshallian labor market pooling: Evidence from Italy

(with Monica Andini, Guido de Blasio and William C Strange)  Abstract 

Regional Science and Urban Economics, 2013, 43(6), 10008-1022

 

This paper employs a unique Italian data source to take a comprehensive approach to labor market pooling. It jointly considers many different aspects of the agglomeration labor market relationship, including turnover, learning, matching, and hold up. It also considers labor market pooling from the perspective of both workers and firms and across a range of industries. Overall, the paper finds some support for theories of labor market pooling, but the support is weak. Specifically, there is a general positive relationship of turnover to local population density, which is consistent with theories of agglomeration and uncertainty. There is also evidence of onthejob learning that is consistent with theories of labor pooling, labor poaching, and hold up. In addition, the paper provides evidence consistent with agglomeration improving job matches. However, the labor market pooling gains that we measure are small in magnitude and seem unlikely to account for a substantial share of the agglomeration benefits accruing to Italian worker and firms.

The productivity advantages of large cities: Distinguishing agglomeration from firm selection

(with Pierre-Philippe Combes, Laurent Gobillon, DiegoPuga, and Sébastien Roux)  Abstract 

Econometrica 2012, 80(6), 2543-2594

Firms are more productive, on average, in larger cities. Two main explanations have been offered: firm selection (larger cities toughen competition, allowing only the most productive to survive) and agglomeration economies (larger cities promote interactions that increase productivity), possibly reinforced by localized natural advantage. To distinguish between them, we nest a generalized version of a tractable firm selection model and a standard model of agglomeration. Stronger selection in larger cities left-truncates the productivity distribution, whereas stronger agglomeration right-shifts and dilates the distribution. Using this prediction, French establishment-level data, and a new quantile approach, we show that firm selection cannot explain spatial productivity differences. This result holds across sectors, city size thresholds, establishment samples, and area definitions.


Urban growth and transportation

(with Matt Turner)  Abstract 

Review of Economic Studies, 2012, 79(4), 1407-1440

We estimate the effects of interstate highways on the growth of U.S. cities between 1983 and 2003. We find that a 10% increase in a city’s initial stock of highways causes about a 1.5% increase in its employment over this 20 year period. To estimate a structural model of urban growth and transportation, we rely on an instrumental variables estimation that uses a 1947 plan of the interstate highway system, an 1898 map of railroads, and maps of the early explorations of the U.S. as instruments for 1983 highways.


Sorting and local wage and skill distributions in France

(with Pierre-Philippe Combes, Laurent Gobillon, and Sébastien Roux)  Abstract 

Regional Science and Urban Economics, 2012, 42(6), 913-930

This paper provides descriptive evidence about the distribution of wages and skills in denser and less dense employment areas in France. We confirm that on average, workers in denser areas are more skilled. There is also strong over-representation of workers with particularly high and low skills in denser areas. These features are consistent with patterns of migration including negative selection of migrants to less dense areas and positive selection towards denser areas. Nonetheless migration, even in the long-run, accounts for little of the skill differences between denser and less dense areas. Finally, we find marked differences across age groups and some suggestions that much of the skill differences across areas can be explained by differences between occupational groups rather than within.


The effects of land transfer taxes on real estate markets: Evidence from a natural experiment in Toronto

(with Benjamin Dachis and Matt Turner)  Abstract 

Journal of Economic Geography, 2012, 12(2), 327-354

Taxes levied on the sale or purchase of real estate are pervasive but little studied. By exploiting a natural experiment arising from Toronto’s imposition of a Land Transfer Tax (LTT) in early 2008, we estimate the impact of real estate transfer taxes on the market for single family homes. Our data show that Toronto’s 1.1% tax caused a 15% decline in the number of sales and a decline in housing prices about equal to the tax. Relative to an equivalent property tax, the associated welfare loss is substantial, about 1forevery8 in tax revenue. The magnitude of this welfare loss is comparable to those associated with better known interventions in the housing market. Unlike many possible tax reforms, eliminating existing LTTs in favour of revenue equivalent property taxes appears straightforward.


The fundamental law of road congestion: Evidence from U.S. cities

(with Matt Turner)  Abstract 

American Economic Review, 2011, 101(6), 2616-2652

We investigate the effect of lane kilometers of roads on vehicle-kilometers traveled (VKT) in US cities. VKT increases proportionately to roadway lane kilometers for interstate highways and probably slightly less rapidly for other types of roads. The sources for this extra VKT are increases in driving by current residents, increases in commercial traffic, and migration. Increasing lane kilometers for one type of road diverts little traffic from other types of road. We find no evidence that the provision of public transportation affects VKT. We conclude that increased provision of roads or public transit is unlikely to relieve congestion. (JEL R41, R48)


Assessing the effects of local taxation using microgeographic data

(with Henry Overman and Laurent Gobillon)  Abstract 

Economic Journal, 2011, 121(555), 1017-1046

We study the impact of local taxation on the location and growth of firms. Our empirical methodology pairs establishments across jurisdictional boundaries to estimate the impact of taxation. Our approach improves on existing work as it corrects for unobserved establishment heterogeneity, for unobserved time-varying site-specific effects and for the endogeneity of local taxation. Applied to data for English manufacturing establishments, we find that local taxation has a negative impact on employment growth but no effect on entry.


California dreamin’: The feeble case for cluster policies

 Abstract 

Review of Economic Analysis, 2011, 3(1), 3-45

This study examines the case for cluster policy. This case is theoretically ambiguous and empirically very weak.


The identification of agglomeration economies

(with Pierre-Philippe Combes, and Laurent Gobillon)  Abstract 

Journal of Economic Geography, 2011, 11(2), 253-266

Measures of urban productivity are typically positively associated with city population. But is this relationship causal? We discuss the main sources of bias in the proper identification of agglomeration effects. We also assess a variety of solutions that have been proposed in the literature to deal with them.


Is the division of labour limited by the extent of the market? Evidence from French cities

(with Hubert Jayet)  Abstract 

This paper provides supportive evidence to the notion that the division of labour is limited by the extent of the (local) market. We first propose a theoretical model. Its main prediction is that scarce specialists occupations are over-represented in large cities. Using census data for French cities, we find strong empirical support for this prediction.


The economics of clusters: Evidence from France

(with Philippe Martin, Thierry Mayer, and Florian Mayneris)  Abstract 

Book, Oxford University Press, 2010

The development of clusters of economic activity is an important feature of industrial policy. Industry clusters have long fascinated economists and geographers alike, the most renowned being Silicon Valley which is seen by many as the blueprint for regional development, innovation, and growth. Several clusters have also developed across Europe, including SiliconFen in Cambridge and Minalogic in Grenoble, and in recent years cluster policies have become popular among policy makers as a useful tool for informing decisions on industrial, regional, and public policy. This book looks at the mechanisms at work behind cluster dynamics, the gains that can be expected from increased clustering, and the determinants of cluster policies. Focusing on France, it provides a theoretical and empirical study of clusters, their success and failures, and the policy lessons that can be applied to the wider international community. France is particularly interesting because there is a long tradition of strong government intervention regarding the location of economic activity, and cluster initiatives are relatively unified across the country. This book shows that, whilst gains from clusters do exist, some firms tend to cluster too much and that spatial agglomeration is only successful to a point, after which congestion effects can offset these gains. It questions the need and the feasibility of cluster policies aimed at interfering directly in the concentration process of firms, and thus looks beyond the general enthusiasm for clusters.


Estimating agglomeration economies with history, geology, and worker effects

(with Pierre-Philippe Combes, Laurent Gobillon, and Sébastien Roux)

Chapter in The Economics of Agglomeration, edited by Ed Glaeser, NBER and University of Chicago Press, 2010


From cities to productivity and growth in developing countries

 Abstract 

Canadian Journal of Economics, 2008, 41(3), 689-736

This paper reviews the evidence about the effects of urbanization and cities on productivity and economic growth in developing countries using a consistent theoretical framework. As in developed economies, there is strong evidence that cities in developing countries bolster productive efficiency. Regarding whether cities promote self-sustained growth, the evidence is suggestive but ultimately inconclusive. These findings imply that the traditional agenda of aiming to raise within-city efficiency should be continued. Furthermore, reducing the obstacles to the reallocation of factors across cities is also desirable.


Spatial wage disparities: Sorting matters!

(with Pierre-Philippe Combes and Laurent Gobillon)  Abstract 

2008, 63(2), 723-742

Spatial wage disparities can result from spatial differences in the skill composition of the workforce, in non-human endowments, and in local interactions. To distinguish between these explanations, we estimate a model of wage determination across local labour markets using a very large panel of French workers. We control for worker characteristics, worker fixed effects, industry fixed effects, and the characteristics of the local labour market. Our findings suggest that individual skills account for a large fraction of existing spatial wage disparities with strong evidence of spatial sorting by skills. Interaction effects are mostly driven by the local density of employment. Not controlling for worker heterogeneity leads to very biased estimates of interaction effects. Endowments only appear to play a small role.


Exploring the detailed location patterns of U.K. manufacturing industries using microgeographic data

(with Henry Overman)  Abstract 

Journal of Regional Science, 2008, 48 (1), 313 – 343

We use a point-pattern methodology to explore the detailed location patterns of U.K. manufacturing industries. In particular, we consider the location of entrants and exiters versus continuing establishments, domestic- versus foreign-owned, large versus small, and affiliated versus independent. We also examine colocalization between vertically-linked industries. Our analysis provides a set of new stylized facts and confirmation for others.


Rising trade costs? Agglomeration and trade with endogenous transaction costs

(with Michael Storper)  Abstract 

Canadian Journal of Economics, 2008, 41 (1), 292 – 319

While transport costs have fallen, the empirical evidence also points at rising total trade costs. In a model of industry location with endogenous transaction costs that seeks to replicate features from the machinery industry, we show how and under which conditions a decline in transport costs can lead to an increase in the total cost of trade. The subtle relationship between (endogenous) transport costs and the sensitivity of trade to distance is also explored.


Urban evolutions: The fast, the slow, and the still

 Abstract 

American Economic Review, 2007, 97 (1), 197-221

With the use of French and US data, new and systematic evidence is provided about the rapid location changes of industries across cities (the fast). Cities are also slowly moving up and down the urban hierarchy (the slow), while the size distribution of cities is skewed to the right and very stable (the still). The model proposed here reproduces these three features. Small, innovation-driven shocks lead to the churning of industries across cities. Then, cities slowly grow or decline following net gains or losses of industries. These changes occur within a stable distribution. The quantitative implications of the model are also explored. (JEL R12, R32)


Some foundations for Zipf’s law: Product proliferation and local spillovers

 Abstract 

Regional Science and Urban Economics, 2006, 36(4), 543-563

This paper embeds the canonical model of endogenous growth with product proliferation developed by Romer [Romer, P.M., 1990. Endogenous technical change. Journal of Political Economy 98, S71–S102] into a simple urban framework. This yields a reduced form isomorphic to the popular statistical device developed by Simon [Simon, H., 1955. On a class of skew distribution functions. Biometrika 42, 425–440], which in turn can yield Zipf’s law for cities. The stochastic outcomes of purposeful innovation and local spillovers can thus serve as foundations for random growth models.


Cities and workplace communication: Some quantitative French evidence

(with Sylvie Charlot)  Abstract 

Urban Studies, 2006, 43(8), 1365-1394

This paper uses a unique labour force survey to document workplace communication patterns in urban, suburban and rural areas. A number of interesting stylised facts are distilled relating to workplace communication: its intensity, within-firm communication, communication external to the firm and the media being used with a special focus on information technologies. The paper also investigates the complementarities across different media of communication and the evolution over time of workplace communication patterns. It is found that cities foster communication external to the firm and the use of telecommunications. By contrast, the hypothesis of a greater prevalence of face-to-face communication in cities does not receive much empirical validation. Also, complementarities across media do not lend much support to popular predictions about the forthcoming demise of cities following the replacement of face-to-face meetings by telecommunications.


Labour pooling, labour poaching, and spatial clustering

(with Pierre-Philippe Combes)  Abstract 

Regional Science and Urban Economics, 2006, 36(1), 1-28

When firms cluster in the same local labour market, they face a trade-off between the benefits of labour pooling (i.e., access to workers whose knowledge help reduce costs) and the costs of labour poaching (i.e., loss of some key workers to competition and a higher wage bill to retain the others). We explore this tradeoff in a duopoly game. Depending on market size, on the degree of horizontal differentiation between goods, and on worker heterogeneity in terms of knowledge transfer cost, we characterise the strategic choices of firms regarding locations, wages, poaching and prices. Our results show that co-location, although it is always efficient in our framework, is not in general the non-cooperative equilibrium outcome.


Agglomeration and the adjustment of the spatial economy

(with Pierre-Philippe Combes and Henry Overman)  Abstract 

Papers in Regional Science, 2005, 84(3), 311-349

 

We consider the literature on urban systems and New Economic Geography to examine questions concerning agglomeration and how areas respond to shocks to the economic environment. We first propose a diagrammatic framework to compare the two approaches. We then use this framework to study a number of extensions and to consider several policy relevant issues.

Testing for localisation using micro-geographic data

(with Henry Overman)  Abstract 

Review of Economic Studies, 2005, 72(4), 1077-1106

To study the detailed location patterns of industries, and particularly the tendency for industries to cluster relative to overall manufacturing, we develop distance-based tests of localization. In contrast to previous studies, our approach allows us to assess the statistical significance of departures from randomness. In addition, we treat space as continuous instead of using an arbitrary collection of geographical units. This avoids problems relating to scale and borders. We apply these tests to an exhaustive U.K. data-set. For four-digit industries, we find that (i) 52% of them are localized at a 5% confidence level, (ii) localization mostly takes place at small scales below 50 km, (iii) the degree of localization is very skewed, and (iv) industries follow broad sectoral patterns with respect to localization. Depending on the industry, smaller establishments can be the main drivers of both localization and dispersion. Three-digit sectors show similar patterns of localization at small scales as well as a tendency to localize at medium scales.


From sectoral to functional urban specialisation

(with Diego Puga)  Abstract 

Journal of Urban Economics, 2005, 57(2), 343-370

Striking evidence is presented of a previously unremarked transformation of urban structure from mainly sectoral to mainly functional specialisation. We offer an explanation showing that this transformation is inextricably interrelated with changes in firms’ organisation. A greater variety of business services for headquarters and of sector-specific intermediates for production plants within a city reduces costs, while congestion increases with city size. A fall in the costs of remote management leads to a transformation of the equilibrium urban and industrial structure. Cities shift from specialising by sector—with integrated headquarters and plants—to specialising mainly by function—with headquarters and business services clustered in larger cities, and plants clustered in smaller cities.


Communication externalities in cities

(with Sylvie Charlot)  Abstract 

Journal of Urban Economics, 2004, 56(3), 581-613

To identify communication externalities in French cities, we exploit a unique survey recording workplace communication of individual workers. Our hypothesis is that in larger and/or more educated cities, workers should communicate more. In turn, more communication should have a positive effect on wages. By estimating both an earnings and a communication equation, we find evidence of communication externalities. In larger and more educated cities, workers communicate more and in turn this has a positive effect on their wages. Depending on the estimates, we find that 13 to 22% of the effects of a more educated and larger city on wages percolate through this channel.


Microfoundations of urban agglomeration economies

(joint with Diego Puga)  Abstract 

Handbook of Regional and Urban Economics, Volume 4, 2004, edited by J. V. Henderson and J.-F. Thisse, 2063-2117.

This handbook chapter studies the theoretical micro-foundations of urban agglomeration economies. We distinguish three types of micro-foundations, based on sharing, matching, and learning mechanisms. For each of these three categories, we develop one or more core models in detail and discuss the literature in relation to those models. This allows us to give a precise characterisation of some of the main theoretical underpinnings of urban agglomeration economies, to discuss modelling issues that arise when working with these tools, and to compare different sources of agglomeration economies in terms of the aggregate urban outcomes they produce as well as in terms of their normative implications.


Mind the gaps: The evolution of regional inequalities in the U.K. 1982-1997

(with Vassilis Monastiriotis)  Abstract 

Journal of Regional Science, 2002, 42(2), 219-256

In this paper we apply earnings equations for U.K. regions over 1982–1997. We find evidence of rapid convergence across regions regarding the determinants of individual wages (i.e., regional fixed-effects, gender gaps, and returns to education and experience). In contrast, data on average regional earnings point to a worsening of U.K. regional inequalities and a rise in the North-South gap. Education accounts for most of the discrepancy between aggregate divergence and disaggregated convergence. First, London gained because its workforce became relatively more educated over the period. Second, returns to education increased nationwide, which favored the most educated regions (i.e., London). Third, returns to education were initially lower in London but they (partially) caught up with the rest of the country. Had returns to education and their distribution across U.K. regions remained stable over the period, the U.K. North-South divide would have decreased.


Nursery cities: Urban diversity, process innovation, and the life-cycle of product

(with Diego Puga)  Abstract 

American Economic Review, 2001, 91(5), 1454-1477

This paper develops microfoundations for the role that diversified cities play in fostering innovation. A simple model of process innovation is proposed, where firms learn about their ideal production process by making prototypes. We build around this a dynamic general-equilibrium model, and derive conditions under which diversified and specialized cities coexist. New products are developed in diversified cities, trying processes borrowed from different activities. On finding their ideal process, firms switch to mass production and relocate to specialized cities where production costs are lower. We find strong evidence of this pattern in establishment relocations across French employment areas 1993-96.


Diversity and specialisation in cities: Why, where and when does it matter?

(with Diego Puga)  Abstract 

Urban Studies, 2000, 37 (3), 533-555

Why are some cities specialised and others diversified? What are the advantages and disadvantages of urban specialisation and diversity? To what extent do the structure of cities and the activities of firms and people in them change over time? How does the sectoral composition of cities influence their evolution? To answer these and related questions, we first distil some key stylised facts from the empirical literature on cities and the composition of their activities. We then turn to a review of different theories looking at such issues, and study the extent to which these theories contribute to the understanding of the empirical regularities.


Urban structure, urbanization and growth

 Abstract 

Chapter in Economics of Cities, edited by J.-M. Huriot and J. Thisse, Cambridge University Press, 2000

Since cities are likely to play an even more predominant role in the global economy in the future than they do at present, it is important to understand how urban centers are created, grow, and function in the process of generating and distributing wealth. This integrated collection of essays exploring the economic theory of cities assembles work by a number of the world’s leading exponents in North America, the UK/Europe, and Japan. Topics investigated include cities and agglomeration, urban systems, urbanization and growth, and cities and factor markets. The perspectives the editors and contributors offer have strong connections with several branches of modern economics, including industrial organization, public economics, international trade, and endogenous growth and economic development.


Distance, land, and proximity: Economic analysis and the evolution of cities
 Abstract 

Environment and Planning A, 1999, 31 (12), 2169-2188

The author attempts to provide a synthesis of the long-run evolution of cities by taking an economic perspective. He defends the idea that urban growth for preindustrial cities has been limited by the tyranny of distance. Then he argues that technological progress, by fostering mobility, has reinforced economies of agglomeration and thus allowed for larger cities. This has led to the development of industrial cities and the dominance of the tyranny of distance. Nowadays, however, technological progress in communications and telecommunications seems to be challenging the rationale for agglomeration in cities as more and more economic interactions can be realized at arm’s length. Increasing mobility may have turned into a threat for cities, hence the prediction about the demise of cities. Nonetheless, it is argued that the `tyranny of proximity’ may provide a strong glue to keep postindustrial cities together.


Financing productive local public goods

(with S. Déo)  Abstract 

Journal of Urban Economics, 1999, 45 (2), 264-286

Public economics typically assumes that local public goods only affect the utility of consumers. We analyze the case of purely productive local public goods within standard growth models. Investment in the public good enhances productivity only in the jurisdiction where it takes place. Capital, as well as people, is perfectly mobile. After characterizing the first-best equilibrium, we show that its decentralization to fiscally independent jurisdictions is more demanding than with local public consumer goods. In particular, efficient decentralization cannot be obtained with competitive land developers providing the public good through a simple land capitalization scheme.


Labor specialization, transports costs and city size

 Abstract 

Journal of Regional Science, 1998, 38 (4), 553-575

This paper proposes a simple model of pre-industrial urbanization. Agglomeration stems from increasing returns generated by the specialization of labor, whereas dispersion is provoked by the transport costs of the agricultural good. Considering the existence of some urban institutions (in particular guilds), the equilibrium size of cities is derived and it is efficient. Within this framework, the effects of urban domination (e.g., taxation of agriculture) and the emergence of primate cities are explored. Finally, the transition between early and modern urbanization is studied.