Gilles Duranton

Micro-Foundations of Urban Agglomeration Economies

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.

Testing for Localization Using Micro-Geographic Data

To study the detailed location patterns of industries, and particularly the tendency for industries to cluster relative to overallmanufacturing, we develop distance-based tests of localisation. 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 localised at a 5% confidence level, (ii) localisation takes place mostly at small scales below 50 kilometres, (iii) the degree of localisation is very skewed, and (iv) industries follow broad sectoral patterns with respect to localisation. Depending on the industry, smaller establishments can be the main drivers of both localisation and dispersion. Three-digit sectors show similar patterns of localisation at small scales as well as a tendency to localise at medium scales.

Diversity and Specialisation in Cities: Why, Where and When Does it Matter?

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.

The Productivity Advantages of Large Cities: Distinguishing Agglomeration from Firm Selection

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 localised natural advantage. To distinguish between them, we nest a generalised 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.

Exploring the Detailed Location Patterns of UK Manufacturing Industries using Microgeographic Data

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Productive Cities: Sorting, Selection, and Agglomeration

Large cities produce more output per capita than small cities. This higher productivity 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 systems of cities that combines all three elements and suggests interesting complementarities between them. The model can replicate stylized facts about sorting, agglomeration, and selection in cities. It also generates Zipf’s law for cities under empirically plausible parameter values. Finally, it provides a useful framework within which to reinterpret extant empirical evidence.

Mind the Gaps: The Evolution of Regional Earnings Inequalities in the U.K., 1982-1997

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.

Assessing the Effects of Local Taxation using Microgeographic Data

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.

The Growth of Cities

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.

Family Types and the Persistence of Regional Disparities in Europe

abstract 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.