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Complex economic activities concentrate in large cities


Human activities, such as research, innovation and industry, concentrate disproportionately in large cities. The ten most innovative cities in the United States account for 23% of the national population, but for 48% of its patents and 33% of its gross domestic product. But why has human activity become increasingly concentrated? Here we use data on scientific papers, patents, employment and gross domestic product, for 353 metropolitan areas in the United States, to show that the spatial concentration of productive activities increases with their complexity. Complex economic activities, such as biotechnology, neurobiology and semiconductors, concentrate disproportionately in a few large cities compared to less--complex activities, such as apparel or paper manufacturing. We use multiple proxies to measure the complexity of activities, finding that complexity explains from 40% to 80% of the variance in urban concentration of occupations, industries, scientific fields and technologies. Using historical patent data, we show that the spatial concentration of cutting-edge technologies has increased since 1850, suggesting a reinforcing cycle between the increase in the complexity of activities and urbanization. These findings suggest that the growth of spatial inequality may be connected to the increasing complexity of the economy.

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Fig. 1: Spatial concentration of activities.
Fig. 2: Urban concentration increases with knowledge complexity.
Fig. 3: Evolution of the urban scaling of technologies.

Data availability

The data that support the findings of this study are available from the corresponding author upon request.

Code availability

The code that supports the findings of this study is available from the corresponding author upon request.


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We thank Ö. Nomaler, K. Frenken and G. Heimeriks for providing the data on scientific publications used in the main text, and G. Patience, C. Patience, B. Blais and F. Bertrand for providing the data on the age of references listed in scientific publications. We also thank R. Boschma, K. Frenken, M. Storper, A. J. Scott, T. Broekel, B. Jun, F. Pinheiro, A. Alshamsi and F. Neffke for useful comments and suggestions. Financial support from the Regional Studies Association through the Early Career Grant awarded to P.-A.B. is gratefully acknowledged. C.A.H. acknowledges support from the MIT Media Lab consortia, from the MIT-Skoltech seed grant and from the MIT-Masdar initiative. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

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P.-A.B., C.J.-F., S.G.P., M.P.A.S., D.L.R. and C.A.H. all contributed equally to the work and have supervised it jointly.

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Correspondence to Pierre-Alexandre Balland.

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Peer review information Primary Handling Editors: Mary Elizabeth Sutherland; Stavroula Kousta.

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Balland, PA., Jara-Figueroa, C., Petralia, S.G. et al. Complex economic activities concentrate in large cities. Nat Hum Behav 4, 248–254 (2020).

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