by Shlomo Angel and Alejandro M. Blei

Abstract: Urban transport and land use policy are informed by our perceptions of the prevailing spatial structure of cities. This structure can be characterized by five models: The Maximum Disorder model, The Mosaic of Live-Work Communities model, the Monocentric City model, the Polycentric City model, and the Constrained Dispersal model, where the great majority of jobs are dispersed throughout the metropolitan area and where workers and workplaces in a metropolitan-wide labor market adjust their locations to be within an tolerable commute range of each other. We examine evidence from a stratified sample of 40 U.S. cities and from the 50 largest U.S. cities to show that the latter model best explains the spatial structure of contemporary American cities. The Constrained Dispersal model is, in essence, a hybrid model that combines elements of all other models. It postulates that the Maximum Disorder model is largely correct, except that it applies only to 3 out of 4 jobs but not to all jobs, and except that commuters and workplaces move to be within a tolerable commute distance of each other. It postulates that the Mosaic of Live-Work Communities model is also correct, except that it only applies to 1 out of 12 people, on average, who live and work in the same community. It postulates that the Monocentric City model is also correct, except that only 1 out of 9 jobs, on average—rather than all jobs—still locate at the CBD. And it postulates that the Polycentric City model is also correct, except that only 1 out of 4 jobs, on average—rather than to all jobs—locate in the CBD or in employment sub-centers. In essence, the great majority of workplaces is now dispersed outside CBDs, employment sub-centers or live-work communities, and is beyond walking or biking distance. Maintaining and increasing the productivity of American cities requires a sustained focus on meeting the travel demands of the great majority of commuters rather than on improving mobility at large or on transportation strategies focused on CBDs, employment sub-centers, or live-work communities.

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by Shlomo Angel and Alejandro M. Blei

Abstract: The greatest productive advantage of modern-day American cities is that they form large and integrated metropolitan labor markets. We present new evidence on the importance of self-adjusting commuting and location patterns in sustaining the productive advantages of larger metropolitan labor markets, mitigating the difficulties in coping with their sheer size, and reducing the added burdens on their transportation infrastructure. As a result of these adjustments, the metropolitan labor market—defined as the actual number of jobs in the metropolitan area reached in less than a 1-hour commute—almost doubles in size when the workforce in a U.S. city doubles. More particularly, when U.S. metropolitan areas double in population, commute time should be expected to increase by a factor equal to the square root of 2. Instead, it only increases by one-sixth of that factor because of three types of adjustments that take place as cities grow in population: increases in residential density, locational adjustments of residences and workplaces to be within a tolerable commute range of each other, and increases in commuting speeds brought about by shifts to faster roads and transit systems. The policy implications of these findings are that the more integrated metropolitan labor markets are, the more productive they are. We should therefore support policies that increase overall regional connectivity; policies that allow for speedier rather than slower commuting, for more rather than less commuting, and for longer rather shorter commuting to take advantage of metropolitan-wide economic opportunities; and policies that remove impediments to the locational mobility of residences and workplaces for all income groups so that they can easily relocate to be within tolerable commute range of each other.

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Abstract: Using a novel methodology, we study the changes in the population densities of the built-up areas of Manhattan and its neighborhoods from 1800 to 2010. Built-up areas were determined from historical maps, insurance maps, and air photographs, while population data were collected for census wards from 1790 to 1910 and for census tracts thereafter. We found that densities remained stable, at 200 persons per hectare, until 1840 when the growth in the built-up area could no longer keep up with rapid population growth. By 1910, average densities in Manhattan were triple those of 1840, while average densities in some neighborhoods were twice as high and more. Densities then started to decline, largely due to three public actions: the annexation of Brooklyn, Queens, the Bronx and Richmond County to Manhattan in 1898; the creation of vast new areas for urban expansion in the 1900 Topographical Bureau plan; and the building of the subway system from 1904 onwards. These actions led to the rapid decongestion of Manhattan’s overcrowded neighborhoods, as lower-income workers suburbanized while still commuting to Manhattan on a nickel fare. Densities in Manhattan declined until 1980 and have risen slightly since. New York City is now expecting a significant increase in population, entailing significant densification in Manhattan and elsewhere. Using the lessons learned from our study, we outline a densification program that could accommodate a larger population without recourse to heavy-handed land assembly for large and heavily subsidized housing projects. Our strategy is based on our conviction that we can achieve a more efficient, more equitable, and more sustainable densification in New York City with small actions on the part of the many than with big actions on the part of the few.

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Article in: Environment and Urbanization 

Authors: Shlomo Angel, Jason Parent, and Daniel L. Civco

First published: 2012

Pages: 249-283

Overview:  A key question that has confronted urban planners, policy makers and concerned environmentalists worldwide for some time is whether the fragmentation of the urban landscape is an inherent feature of contemporary cities that must be taken into account in planning for and managing urban expansion, or whether it is a disorderly, wasteful and undesirable form of sprawl that must be brought under control through containment or growth management strategies of one type or another.

Full Text: The Fragmentation of Urban Landscapes (PDF)

Article in: China’s Housing Reform and Outcomes

Authors: Shlomo Angel, Midori Valdiva, and Rebecca M. Lutzy

First published: 2011

Pages: 137-156

Overview:  This volume provides background and explanations about the causes and consequences of China’s boom in residential construction, and it reviews how some well-established and ongoing trends are likely to impact China’s housing sector in coming years.

Full Text: Urban Expansion, Land Conversion, and Affordable Housing (PDF)

Article in: Climate Change and Land Policies

Authors: Shlomo Angel, A.M. Blei, J. Parent, and D.L. Civco

First published: 2011

Pages: 191-210

Overview: A century of density decline in U.S. metropolitan areas has posed structural challenges to the provision of transit services.  This article shows that both the share of the metropolitan populations that can sustain transit and the share of metropolitan ares that can sustain transit have declined substantially over time and are now exceedingly low in most U.S. metropolitan areas.

Full Text: The Fragmentation of Urban Landscapes (PDF)

Article in: Northwestern Interdisciplinary Law Review 4 (1)

Authors: Shlomo Angel, Jason Parent

First published: 2011

Pages: 89-130

Overview: This essay proposes a novel compactness standard “for courts to identify at least the worst cases of gerrymandering and to provide a remedy.” This standard is based on the perception of gerrymandering as aggressive voter exchange, an exchange that distorts the shapes of election districts and renders them non-compact by expelling voters living close by and exchanging them for voters living further away.

Full Text: Non-Compactness and Voter Exchange (PDF)

Article in: Progress in Planning, Volume 75, Issue 2

Authors: Shlomo Angel, J. Parent, D. L. Civco, A.M. Blei and D. Potere

First published: 2011

Pages: 53-108

Overview: The rapid growth in global urban land cover is likely to continue as long as urban populations continue to grow, as long as incomes continue to rise, and as long as urban transport remains relatively cheap and affordable.  This article therefore seeks to refocus the attention of planners, policy makers and concerned activists on urban expansion in developing countries and to begin to examine its policy implications.

Full Text: The Dimensions of Global Urban Expansion (PDF)

Article Information: Prepared for the government of Belize and the World Bank

Authors: Shlomo Angel, Stephen C. Sheppard and Daniel L. Civco, with Robert Buckley, Anna Chabaeva, Lucy Gitlin, Alison Kraley, Jason Parent, and Micah Perlin

Date: January, 2010

Overview: This report is an assessment of the housing sector and the housing policy environment in Belize at the present time. Its practical and immediate goal is to provide a useful analysis of the housing sector in Belize focused on its parameters, potentials, and pitfalls, in order to assist the Government as well as the various stakeholders in the housing sector in moving together towards ensuring “access to quality and affordable housing by all” in the coming years.

Full Text (unpublished): Housing Policy in Belize: Diagnosis and Guidelines for Action (PDF)

Article in: Canadian Geographer 54

Authors: Shlomo Angel, Jason Parent, and Daniel L. Civco

First published: 2010

Pages: 441-461

Overview: This essay sheds new light on the meaning and measurement of compactness—one of the most intriguing and least-understood properties of geographic shapes. We articulate a unified theoretical foundation for the study of shape compactness that rests on two simple observations: First, that the circle is the most compact of shapes. And second, that there are 10—and possibly more—distinct geometrical properties of the circle that make it the most compact of shapes. We introduce these 10 properties, illustrate them with real-world examples and define indices associated with these properties that can be calculated using a geographic information system.

Full Text: Ten Compactness Properties of Circles (PDF)