• Selected
• Entire List

Abstract:
Why are some cities specialised and others diversified? What are the advantages and disadvantages of urban specialisation and diversity? To what extent does 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.

Abstract:
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.

Cities, agglomeration, increasing returns, micro-foundations

Abstract:
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.

Abstract:
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.

Abstract:
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 UK data set. For four-digit industries, we find that (i) only 51% of them are localized at a 5% confidence level, (ii) localization takes place mostly at small scales below 50 kilometres, (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.

Localization, clusters, K-density, spatial statistics

Abstract:
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.

Abstract:
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, we show how and under which conditions a decline in transport costs can lead to an increase in the total cost of trade.

Transaction costs, trade costs, transport costs, agglomeration, vertically linked industries

Abstract:
We document and then develop a model explaining and relating changes in firms' organization and in urban structure. Sharing of business services by headquarters and of sector-specific intermediates by production plants within a city reduces costs, while congestion increases with city size. A fall in the costs of remote management leads to a shift in urban structure, from a configuration where cities specialize by sector and host integrated headquarters and production plants, to a configuration where cities specialize by function, with headquarters from different sectors and business services clustered in a few large cities and production plants from each sector clustered in smaller separate cities.

Functional specialisation, cities, business services, headquarters

Abstract:
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.

Abstract:
We consider the literatures 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.

Urban systems, new economic geography, urban and regional policy, diagrammatic exposition

Abstract:
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.

Abstract:
Striking evidence is presented of a previously unremarked transformation of urban structure from mainly sectoral to mainly functional specialization. We offer an explanation showing that this transformation is inextricably interrelated with changes in firms' organization. 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 specializing by sector - with integrated headquarters and plants - to specializing mainly by function - with headquarters and business services clustered in larger cities, and plants clustered in smaller cities.

Abstract:
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.

Local taxation, spatial differencing, borders, regression discontinuity

Abstract:
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 biases estimates of agglomeration economies by up to 100%. We also find evidence of various omitted variable biases and reverse causality between agglomeration and high wages. Finally, endowments only appear to play a small role.

Local labour market, spatial wage disparities, panel data analysis, sorting

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

Localisation, location patterns, clusters, k-density, spatial statistics

Abstract:
The size distribution of cities in many countries follows some broadly regular patterns. Any good theory of city size distributions should (i) be able to account for this regularity, but also (ii) rely on a plausible economic mechanism and (iii) be consistent with other fundamental features of cities like the existence of agglomeration economies and crowding costs. Unlike the previous literature, the model proposed here satisfies these three requirements. It views small innovation-driven technological shocks as the main engine behind the growth and decline of cities. Cities grow or decline as they win or lose industries following new innovations. Formally, this is achieved by embedding the quality-ladder model of growth developed by Grossman and Helpman (1991) in an urban framework.

City-size distribution, quality-ladder models of growth, agglomeration economies

Abstract:
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 individual wages. By estimating both an earnings and a communication equation, we find evidence of communication externalities. Being in a larger and more educated city makes workers communicate more and in turn this has a positive effects on wages. Only a small fraction of the overall effects of a more educated and larger city on wages percolates through this channel, however.

Human capital, cities, communication externalities

Abstract:
We investigate the relationship between interstate highways and highway vehicle kilometers traveled (vkt) in US cities. We find that vkt increases proportionately to highways and identify three important sources for this extra vkt: an increase in driving by current residents; an increase in transportation intensive production activity; and an inflow of new residents. The provision of public transportation has no impact on vkt. We also estimate the aggregate city level demand for vkt and find it to be very elastic. We conclude that an increased provision of roads or public transit is unlikely to relieve congestion and that the current provision of roads exceeds the optimum given the absence of congestion pricing.

congestion, highways, public transport, vehicle-kilometers traveled

Abstract:
We investigate the relationship between interstate highways and highway vehicle kilometers traveled (VKT) in US cities. We find that VKT increases proportionately to highways and identify three important sources for this extra VKT: an increase in driving by current residents; an increase in transportation intensive production activity; and an inflow of new residents. The provision of public transportation has no impact on VKT. We also estimate the aggregate city level demand for VKT and find it to be very elastic. We conclude that an increased provision of roads or public transit is unlikely to relieve congestion.

Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Abstract:
This paper provides some evidence that the division of labor is limited by the extent of the (local) market. We first propose a theoretical model. Its main prediction is that scarce occupations are over-represented in large cities. Using census data for French cities, we then provide strong empirical support for this prediction.

Division of labor, specialization, extent of the market

Abstract:
When firms cluster in the same local labor market, they face a trade-off between the benefits of labor pooling (i.e., access to workers whose knowledge helps reduce costs) and the costs of labor poaching (i.e., loss of some key workers to competition and the indirect effect of a higher wage bill to retain the others). We explore this trade-off in a duopoly game. Depending on market size and on the degree of horizontal differentiation between products, we characterize the strategic choices of firms regarding locations, wages, poaching and prices. Our results show that co-location, although it is always efficient, is not in general the equilibrium outcome.

Labor pooling, labor poaching, firm clustering, agglomeration

Abstract:
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 co-localization between vertically-linked industries. Our analysis provides a set of new stylized facts and confirmation for others.

Abstract:
Firms are more productive on average in larger cities. Two explanations have been offered: agglomeration economies (larger cities promote interactions that increase productivity) and firm selection (larger cities toughen competition allowing only the most productive to survive). To distinguish between them, we nest a generalised version of a seminal 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. We assess the relative importance of agglomeration and firm selection using French establishment-level data and a new quantile approach. Spatial productivity differences in France are mostly explained by agglomeration.

agglomeration, cities, firm selection, productivity

Abstract:
Does productivity increase with density? We revisit the issue using French wage and TFP data. To deal with the 'endogenous quantity of labour' bias (i.e., urban agglomeration is consequence of high local productivity rather than a cause), we take an instrumental variable approach and introduce a new set of geological instruments in addition to standard historical instruments. To deal with the 'endogenous quality of labour' bias (i.e., cities attract skilled workers so that the effects of skills and urban agglomeration are confounded), we take a worker fixed-effect approach with wage data. We find modest evidence about the endogenous quantity of labour bias and both sets of instruments give a similar answer. We find that the endogenous quality of labour bias is quantitatively more important.

agglomeration economies, instrumental variables, TFP, wages

Abstract:
This paper reviews the evidence about the effects of urbanisation and cities on productivity and economic growth in developing countries using a consistent theoretical framework. Just like 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 and activities, and more generally promoting the movement of human capital and goods across cities may have significant positive dynamic effects as well static ones.

Cities in developing countries, growth, urbanisation

Abstract:
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.

Abstract:
We estimate the effects of major roads and public transit on the growth of major cities in the US between 1980 and 2000. We find that a 10% increase in a city's stock of roads causes about a 2% increase in its population and employment and a small decrease in its share of poor households over this 20 year period. We also find that a 10% increase in a city's stock of large buses causes about a 0.8% population increase and a small increase in the share of poor households over this period. To estimate these effects we rely on an instrumental variables estimation which uses a 1947 plan of the interstate highway system and an 1898 map of railroads as instruments for 1980 roads.

Instrumental variables, public transport, transportation, urban growth

Abstract:
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.