Micro-foundations of urban agglomeration economies Gilles Duranton∗‡ London School of Economics Diego Puga∗§ University of Toronto 11 June 2003 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. Key words: cities, agglomeration, increasing returns, micro-foundations jel classification: r12, r13, r32 ∗This is a draft of a chapter written for eventual publication in the Handbook of Regional and Urban Economics, Volume 4, edited by J. Vernon Henderson and Jacques-François Thisse, to be published by North-Holland. We are grateful to the editors, to Johannes Bröker, Masa Fujita, Mike Peters, Frédéric Robert-Nicoud, and to the participants at the the 2002 narsa meetings for comments and suggestions. ‡Department of Geography and Environment, London School of Economics, Houghton Street, London wc2a 2ae, United Kingdom (e-mail:
[email protected]; website: http://cep.lse.ac.uk/~duranton). Also affiliated with the Centre for Economic Policy Research, and the Centre for Economic Performance at the London School of Economics. §Department of Economics, University of Toronto, 150 Saint George Street, Toronto, Ontario m5s 3g7, Canada (e-mail:
[email protected]; website: http://dpuga.economics.utoronto.ca).