City Size Distributions As A Consequence of the Growth Process

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 techno logical 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 in an urban framework.City size distribution, quality-ladder models of growth, agglomeration economies

From cities to productivity and growth in developing countries

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

California Dreamin': The Feeble Case for Cluster Policies

This study examines the case for cluster policy. This case is theoretically ambiguous and empirically very weak.Clusters, cluster policy, localisation economies, local economic development

Nursery Cities: Urban Diversity, Process Innovation and the Life-Cycle of Products

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 specialised 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 specialised cities with lower costs. When in equilibrium, this configuration welfare-dominates those with only diversified or only specialised cities. We find strong evidence of this relocation pattern in establishment relocations across French employment areas 1993û1996.Cities, diversity, specialisation, innovation, learning, life-cycle

Communication Externalities in Cities

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. However, only a small fraction of the overall effects of a more educated and larger city on wages percolates through this channel.human capital, cities, communication externalities

Nursery Cities: Urban diversity, process innovation, and the life-cycle of products

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 specialised 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 specialised cities where production costs are lower. We find strong evidence of this pattern in establishment relocations across French employment areas 1993-1996.nursery cities; diversity; specialisation; innovation; learning, life-cycle

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.cities; diversity; specialisation

Testing for Localisation Using Micro-Geographic Data

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 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.Localisation, Clusters, K-density, Spatial Statistics.

From sectoral to functional urban specialisation

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.functional specialisation, cities, headquarters, business services