The Coherence of US cities

Fuente: arXiv
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Main Authors: Daniotti, Simone, Hartog, Matte, Neffke, Frank
Format: Preprint
Published: 2025
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author Daniotti, Simone
Hartog, Matte
Neffke, Frank
author_facet Daniotti, Simone
Hartog, Matte
Neffke, Frank
contents Diversified economies are critical for cities to sustain their growth and development, but they are also costly because diversification often requires expanding a city's capability base. We analyze how cities manage this trade-off by measuring the coherence of the economic activities they support, defined as the technological distance between randomly sampled productive units in a city. We use this framework to study how the US urban system developed over almost two centuries, from 1850 to today. To do so, we rely on historical census data, covering over 600M individual records to describe the economic activities of cities between 1850 and 1940, and 8 million patent records as well as detailed occupational and industrial profiles of cities for more recent decades. Despite massive shifts in the economic geography of the U.S. over this 170-year period, average coherence in its urban system remains unchanged. Moreover, across different time periods, datasets and relatedness measures, coherence falls with city size at the exact same rate, pointing to constraints to diversification that are governed by a city's size in universal ways.
format Preprint
id arxiv_https___arxiv_org_abs_2501_10297
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The Coherence of US cities
Daniotti, Simone
Hartog, Matte
Neffke, Frank
Physics and Society
Diversified economies are critical for cities to sustain their growth and development, but they are also costly because diversification often requires expanding a city's capability base. We analyze how cities manage this trade-off by measuring the coherence of the economic activities they support, defined as the technological distance between randomly sampled productive units in a city. We use this framework to study how the US urban system developed over almost two centuries, from 1850 to today. To do so, we rely on historical census data, covering over 600M individual records to describe the economic activities of cities between 1850 and 1940, and 8 million patent records as well as detailed occupational and industrial profiles of cities for more recent decades. Despite massive shifts in the economic geography of the U.S. over this 170-year period, average coherence in its urban system remains unchanged. Moreover, across different time periods, datasets and relatedness measures, coherence falls with city size at the exact same rate, pointing to constraints to diversification that are governed by a city's size in universal ways.
title The Coherence of US cities
topic Physics and Society
url https://arxiv.org/abs/2501.10297