Scaling of Urban Income Inequality in the USA

Heinrich Mora E, Heine C, Jackson JJ, West GB, Yang VC, Kempes CP. 2021 Scaling of urban income inequality in the USA. J. R. Soc. Interface 18: 20210223. https://doi.org/10.1098/rsif.2021.0223

18 Pages Posted: 21 Sep 2021

See all articles by Elisa Heinrich Mora

Elisa Heinrich Mora

Minerva Schools at KGI

Cate Heine

Massachusetts Institute of Technology

Jacob Jackson

Brown University

Geoffrey West

Santa Fe Institute

Vicky Chuqiao Yang

Santa Fe Institute

Chris Kempes

Santa Fe Institute

Date Written: February 25, 2021

Abstract

Urban scaling analysis, the study of how aggregated urban features vary with the population of an urban area, provides a promising framework for discovering commonalities across cities and uncovering dynamics shared by cities across time and space. Here, we use the urban scaling framework to study an important, but under-explored feature in this community — income inequality. We propose a new method to study the scaling of income distributions by analyzing total income scaling in population percentiles. We show that income in the least wealthy decile (10%) scales close to linearly with city population, while income in the most wealthy decile scale with a significantly superlinear exponent. In contrast to the superlinear scaling of total income with city population, this decile scaling illustrates that the benefits of larger cities are increasingly unequally distributed. For the poorest income deciles, cities have no positive effect over the null expectation of a linear increase. We repeat our analysis after adjusting income by housing cost, and find similar results. We then further analyze the shapes of income distributions. First, we find that mean, variance, skewness, and kurtosis of income distributions all increase with city size. Second, the Kullback–Leibler divergence between a city’s income distribution and that of the largest city decreases with city population, suggesting the overall shape of income distribution shifts with city population. As most urban scaling theories consider densifying interactions within cities as the fundamental process leading to the superlinear increase of many features, our results suggest this effect is only seen in the upper deciles of the cities. Our finding encourages future work to consider heterogeneous models of interactions to form a more coherent understanding of urban scaling.

Keywords: scaling laws, urban scaling, power laws, urban inequality, income inequality

Suggested Citation

Heinrich Mora, Elisa and Heine, Cate and Jackson, Jacob and West, Geoffrey and Yang, Vicky Chuqiao and Kempes, Chris, Scaling of Urban Income Inequality in the USA (February 25, 2021). Heinrich Mora E, Heine C, Jackson JJ, West GB, Yang VC, Kempes CP. 2021 Scaling of urban income inequality in the USA. J. R. Soc. Interface 18: 20210223. https://doi.org/10.1098/rsif.2021.0223, Available at SSRN: https://ssrn.com/abstract=3907455 or http://dx.doi.org/10.2139/ssrn.3907455

Elisa Heinrich Mora

Minerva Schools at KGI ( email )

1145 Market St, 9th Floor
San Francisco, CA 94103
United States

Cate Heine

Massachusetts Institute of Technology ( email )

Jacob Jackson

Brown University ( email )

Box 1860
Providence, RI 02912
United States

Geoffrey West

Santa Fe Institute ( email )

1399 Hyde Park Road
Santa Fe, NM 87501
United States

Vicky Chuqiao Yang (Contact Author)

Santa Fe Institute ( email )

1399 Hyde Park Road
Santa Fe, NM 87501
United States

Chris Kempes

Santa Fe Institute ( email )

1399 Hyde Park Road
Santa Fe, NM 87501
United States

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