Urban Studies, from Jacobs to SDG 11

Urban studies is not a single discipline with a settled answer. It is an interdisciplinary field that studies cities — where they come from, how they grow, who they serve, and who they exclude. The opening question this tutorial walks through is the same one a Week 1 lecture at CUHK-Shenzhen's School of Public Policy poses on day one: is the city a triumph, or are cities stretched beyond what they can sustain? We will not resolve that question. What we will do is give you the discipline's coordinates — its founding figures, its vocabulary, its data, its central debate — so that you can ask sharper versions of it in the weeks ahead.

1. Why does urban studies begin on foot?

The discipline's first claim is methodological. Urban studies begins on foot, in the neighbourhood, up close. You cannot understand a city from a satellite image or a dataset alone; you have to walk it. A Chinese contemporary catchphrase, "city walk" (城市漫步 / citywalk), captures the intuition: a "special guided trip for a small group of people, or simply a leisurely stroll for one or two to explore new areas, sticking to the key point: avoiding famous scenic spots and big crowds to gain a more inclusive experience of the places you visit" [ChinaDaily2023]. The slide deck for this Week 1 lecture uses the city walk as its opening device, and two concrete walks are foregrounded: the Jane's Walk at Shekou, Shenzhen, in 2020, and the Jane's Walk at Jingtian North in 2022.

The discipline's canonical ancestor is Jane Jacobs (1916–2006), the New York journalist and activist who, in 1961, published The Death and Life of Great American Cities. The book is the founding text of bottom-up, observational urbanism. Its central move is to argue that the unit of analysis for understanding a city is the street, the block, the small-scale social and economic mix of everyday users JacobsDeath. The discipline has not stopped arguing about that move since.

The Pelican reprint (1965) gives the book its sharpest subtitle: "The Failure of Town Planning." That subtitle frames Jacobs's core argument — that the mid-century planning establishment, the Robert Moses expressway era, the Le Corbusier tower-in-the-park era, was systematically destroying the urban vitality it claimed to build. Jacobs herself fought Moses's expressway plans in New York and the Spadina Expressway in Toronto, and she became a Canadian citizen after moving there in 1968–69 JacobsDeath.

Caption: Jane's Walk, founded in Toronto in 2006 by friends of Jacobs shortly after her death on 25 April 2006, is the institutional carrier of her bottom-up method. As of 2025, the festival takes place in more than 500 cities across more than 70 countries, always on the first weekend of May, aligned with Jacobs's 4 May birthday JacobsDeath. The Shekou and Jingtian North walks pictured here are local instantiations of that global movement.

Jacobs's four conditions of urban diversity

The most-cited contribution of Death and Life is the four conditions of urban diversity, codified in Part Two, chapters 8–11. They are not a causal sequence but a set of necessary conditions that, when combined, produce the "effective economic pools of use" that make city streets feel alive.

Figure: Jacobs's four conditions of urban diversity converge into a vibrant, safe district

The mechanism that makes the conditions operational is what Jacobs calls "eyes on the street" (Part One, chapter 2, "The Uses of Sidewalks: Safety," developed further in chapter 3, "The Uses of Sidewalks: Contact"). Mixed primary uses bring different people onto the sidewalk at different hours, and the informal surveillance of those ordinary users — not the police — is what makes streets safe. The "sidewalk ballet" of ordinary street use (Part One, chapter 2, "The Uses of Sidewalks: Safety") is itself the city's safety, socialisation, and economic mechanism.

The institutional carrier of this method is Jane's Walk, which the slide deck treats as the discipline's working pedagogy. The walk is the unit of observation; the observation is the unit of analysis. Everything else in urban studies — the data, the theory, the policy debates — is downstream of that epistemic stance.

2. What counts as "urban" — and how do we measure it?

If the discipline's first move is observational, its second move is definitional. The word urban is not one thing. The Week 2 required reading for this course, Chen, Orum & Paulsen's Introduction to Cities (Wiley-Blackwell, 2nd edition, 2018), organises the discipline's vocabulary by separating two concepts that slide together in casual speech: places and spaces.

Places are "specific sites, whether entire cities or smaller locations within cities, that are shaped by human beings and shape the lives of human beings." They are the particular, identity-bearing sites where residents form attachment and community. Spaces are "geographic entities with distinct shapes, scales, and other properties that set the stage for certain kinds of human activities." Spaces predispose activity but acquire meaning only through use ChenPaulsen. The book's three dimensions of place — identity, community, security — are the bridge from the abstract vocabulary to the slide deck's "various kinds of boundaries" framing (administrative, socio-cultural, constructed-area 建成区).

The textbook's structure maps cleanly onto the 12 subtopics on slide 10 (origin/evolution, urban culture, urban society, urban environment, urban politics, urban economics, urban/metropolitan space, megacities, planning/design, race/ethnicity/gender, technology, futurism). Across its five parts and fourteen chapters, Jacobs gets a section in Chapter 3 (§3.1, "Jane Jacobs and the discovery of community in the modern metropolis"), the Chicago School gets Chapter 2, Harvey and Castells appear in Chapter 3, the global-cities literature and Shanghai/Dongguan case studies appear in Chapters 11–12, and Detroit/Brooklyn/Shanghai reappear in Chapter 14 ("The remaking and future of cities") ChenPaulsen. The one honest gap to flag: the textbook's 2nd edition was finalised in April 2018, before the contemporary LLM-and-cities wave, so the slide-deck subtopic "Technology and cities (including AI)" does not map cleanly onto any Chen et al. chapter. It is a forward pointer to Week 14, not something this textbook covers.

The UN Degree of Urbanization

Definitions become operational when a statistical agency picks a threshold and starts counting. For decades, the world's countries used 237 different national definitions of "urban," which made cross-country comparison almost meaningless. The fix was the Degree of Urbanization (DEGURBA), a harmonised grid-based methodology that classifies each 1 km² grid cell as a city (≥1,500 inhabitants/km² and ≥50,000 total population), a town or semi-dense area (≥300 inhabitants/km² and ≥5,000 total), or rural (below). DEGURBA was developed jointly by the European Commission, FAO, UN-Habitat, ILO, OECD and the World Bank, and endorsed by the UN Statistical Commission in 2020 for international statistical comparisons UNWUP2025.

This matters because the same country can look very different under its national definition versus DEGURBA. In 2025, the world's national definitions aggregated to 58% urban; DEGURBA put the world at 45% cities plus 36% towns (the cities+towns total of 81% is the DEGURBA analogue of the binary national figure). The gap is largest in Central and Southern Asia and sub-Saharan Africa, where settlements that DEGURBA classifies as towns or cities are still classified as rural in national statistics UNWUP2025. When you read a "67% urban" figure for a country, you need to know which definition is doing the counting.

3. Where is the world in 2025 — and what does the data actually say?

The discipline's data backbone for the global urbanisation question is the UN World Urbanization Prospects (WUP), released by the UN DESA Population Division. The 22nd edition, WUP 2025, was published on 18 November 2025 and supersedes WUP 2018 as the canonical UN source UNWUP2025. This is the first WUP to integrate DEGURBA at the centre of its analysis, and it carries three changes that update the older slide-deck figures you may have seen.

The headline 2025 numbers, on the DEGURBA grid:

• 45% of the world's 8.2 billion people live in cities
• 36% live in towns and semi-dense areas
• 19% live in rural areas

On national definitions aggregated across countries, the figure is 58%. On either metric, the world has crossed an inflection point that took most of human history to reach.

The figure below shows the same trajectory as the WUP 2025 Figure 1.1 time-series chart: three lines for cities (red), towns (yellow/orange) and rural (green), with the 1975 and 1996 crossover annotations directly readable on the chart UNWUP2025.

Caption: World population in billions, 1950–2050, by DEGURBA settlement type. The cities line (red) crosses above the rural line in the mid-1970s and above the towns line in 1996. By 2025 the order is cities > towns > rural; the projection to 2050 keeps cities in the lead at 48% of world population. Source: UN DESA Population Division, World Urbanization Prospects 2025 UNWUP2025.

Two reconciliations worth flagging against older slide-deck figures:

• "65% by 2050" (slide 25) has no exact match in WUP 2025. The closest WUP 2025 endpoints are 67% national-urban, 48% DEGURBA cities, or 61% DEGURBA cities+towns UNWUP2025. The 65% number is a WUP 2018 vintage figure that the slide deck carries forward.
• "2006–2007 crossover" (slide 25) is also a WUP 2018 vintage. WUP 2025 puts the cities-overtake-rural crossover at the mid-1970s on the DEGURBA grid; the 2007 figure was the binary national-definition crossover, which depends on which definition is doing the counting UNWUP2025.

The geographic picture is equally telling. The WUP 2025 Map 1.1 below shows a 2×2 grid of world choropleths in 1975, 2000, 2025, and 2050, with each country coloured by its most common DEGURBA settlement type UNWUP2025.

Caption: In 1975 much of sub-Saharan Africa and South Asia is still green (rural), while North America, Europe, Russia, and Australia are already red (cities). By 2050 the map is overwhelmingly red, with green pockets surviving only in parts of central Africa. The slide deck's map (slide 32) is the same DEGURBA data rendered in a different style.

Two more numbers complete the global picture. WUP 2025 lowered the threshold for tracking an individual urban centre from 300,000 to 50,000 inhabitants, which raised the count of tracked cities from 5,851 in 1975 to 12,140 in 2025 (projected 15,446 by 2050); 96% of these cities have fewer than one million inhabitants, meaning the typical UN city is small, not megacity-scale UNWUP2025. And the megacity count rose from 8 in 1975 to 33 in 2025, with Jakarta now the largest at roughly 42 million, Dhaka second at roughly 37 million, and Tokyo third at 33.4 million — a striking reordering from WUP 2018, where Tokyo was #1 UNWUP2025.

4. Triumph or right to the city — what is the discipline actually arguing about?

The discipline's central debate organises every other urban-studies argument. It runs between a pro-city thesis and a critical-theory counter, and it positions itself around the question: what are cities for?

The pro-city pole is Edward Glaeser's Triumph of the City: How Our Greatest Invention Makes Us Richer, Smarter, Greener, Healthier, and Happier (Penguin Press, hardcover 2011; Penguin Books paperback 2012). The subtitle is the load-bearing thesis: cities are humanity's greatest invention, and they make us better off on five distinct dimensions GlaeserTriumph. Glaeser is an urban economist at Harvard (Fred and Eleanor Glimp Professor of Economics, PhD Chicago 1992), and the book is the popular version of an academic research programme that goes back to his 1998 Journal of Economic Perspectives paper "Are Cities Dying?" GlaeserTriumph.

The book's macro mechanism is what urban economists call agglomeration externalities, two engines that operate only where density is high enough:

Figure: 城市集聚经济:密度催生知识溢出与劳动力池,共同汇成更富更智的城市

Chapter 1, "What Do They Make in Bangalore?", is the accessible entry point: a mid-sized developing-country city becomes a global node for software services by exploiting knowledge spillovers and a deep pool of skilled engineers GlaeserTriumph. The book's normative edge is libertarian-conservative — Glaeser attacks "the dangerous anti-urban political bias" and argues that West Coast land-use regulation has priced too many people out of dense coastal cities GlaeserTriumph. In his chapter on slums, he argues that favelas and historical American ghettos were ports of entry and upward mobility — "urban poverty is an advance over rural poverty" — which is the empirical content behind the slide deck's "cities represent social progress" bullet GlaeserTriumph.

A flag on Glaeser's empirical numbers: the publisher-marketing figures (city dwellers use 40% less energy than suburbanites; more than half of America's income is earned in 22 metropolitan areas) are publisher-controlled marketing copy, not independently audited statistics. Quote them as Glaeser's claims, not as facts GlaeserTriumph.

The counter-weight: Harvey's "right to the city"

The critical-theory counter-tradition runs through Henri Lefebvre's 1968 Le Droit à la ville (Paris: Anthropos) and reaches its canonical 21st-century statement in David Harvey's 2003 IJURR commentary "The Right to the City" (IJURR 27(4):939–941, December 2003, DOI 10.1111/j.0309-1317.2003.00492.x) HarveyRight. Harvey's piece is short — three pages, classified under IJURR's "Interventions" genre — but it carries the discipline's most-quoted line on the relationship between the city and the right:

"The right to the city is not merely a right of access to what already exists, but a right to change it." HarveyRight

Harvey's political-economy move is to frame urbanisation as a class phenomenon. Cities have always arisen through the geographical and social concentration of a surplus product; under capitalism, control over the disbursement of that surplus lies in a few hands. The "right to the city" claim is, on Harvey's reading, a demand for democratic control over the production, distribution, and use of that surplus HarveyRight. This is the move that connects Harvey's 2003 commentary forward to the SDG 11 "off-track" framing we will look at next.

The lineage below visualises how the two sides of the debate sit on a single intellectual map:

Caption: Lefebvre's 1968 Le Droit à la ville (translated into English as Writings on Cities, Blackwell, 1996) is the lineage root; Harvey's 2003 IJURR piece restates the argument in a contemporary register; the post-2008 wave of urban social movements (Occupy, the right-to-the-city networks in Europe and Latin America, UN-Habitat's "right to the city" framing) inherits and applies it HarveyRight.

The two sides are not separate books to be read in isolation. Glaeser's agglomeration thesis and Harvey's right-to-the-city critique are the discipline's two poles, and every other urban-studies argument positions itself somewhere between them. Glaeser optimistically reads the same agglomeration evidence that Harvey reads critically; both are responding to the same phenomenon (cities concentrate wealth and people), and they disagree about who controls the surplus and who has a right to change the city.

5. If cities are a triumph, why is SDG 11 off-track?

The contemporary UN-system verdict on whether the city is a triumph is "off track overall." That is the headline framing of the UN-Habitat SDG 11 Global Report 2026: Housing at the Centre of Sustainable Cities and Communities (108 pages, published 2026) UNHabitat2026. The goal — Sustainable Development Goal 11, "Sustainable Cities and Communities" — sits as one of the 17 UN Sustainable Development Goals adopted in 2015, and the 2026 edition is the third in the SDG 11 Global Report series (after 2018 and 2023).

The chapter asks what the data behind "off-track" actually shows. The picture is mixed: visible progress in public-transport access, municipal waste collection, national urban policy; deepening crisis in housing affordability, slums, public open space, air quality, and disaster mortality UNHabitat2026.

The headline slum figure is one of the most-cited numbers in contemporary urban studies. In 2024, about 1.16 billion urban residents lived in slums or informal settlements — almost one in four urban residents worldwide, over 130 million more than in 2015, and part of a wider housing crisis in which at least 3 billion people live in inadequate housing UNHabitat2026. Without urgent action, the global slum population is projected to exceed 1.2 billion by 2030. The slide-deck's "1.1 billion in slums 2026" is consistent with this; the 1.1 billion is the rounded WUF13 Baku opening figure (17 May 2026 UN News dispatch), while the 1.16 billion is the more recent 2024 baseline now in the SDG 11 Global Report 2026.

The chart below shows the regional breakdown:

Caption: Sub-Saharan Africa (~49% in 2024) and Least Developed Countries (~55%) carry the heaviest slum burden; the world aggregate sits near 24.8% in 2024 and 25.3% in 2015, with the regional shares largely unchanged over the decade UNHabitat2026. Note the chart shows percentages, not absolute headcounts.

The air-quality picture has stalled after a decade of improvement. Global PM2.5 fell from 34.4 µg/m³ in 2010 to 25.4 µg/m³ in 2020, then plateaued at 26.1 µg/m³ in 2023 — about five times the WHO air-quality guideline of 5 µg/m³ UNHabitat2026. The slide deck's "4.2 million ambient air-pollution deaths" figure is the WHO 2016 baseline still cited in 2026; it is not a contemporary count.

Two more numbers from the SDG 11 dashboard complete the picture. Public-transport access, measured across 414 cities in 126 countries, rose from 53.2% in 2020 to 61.5% in 2025 — visible progress, though around 4 in 10 urban residents still lack convenient access UNHabitat2026. Disaster mortality between 2015 and 2024 averaged 41,023 deaths per year and affected 123 million people annually UNHabitat2026. On the negative side, access to open public space across 412 sampled cities in 127 countries fell from 48.0% in 2020 to 45.9% in 2025, and urban green space per capita fell from around 57 m² in 1990 to 28 m² in 2025 UNHabitat2026. On the affordability side, nearly half of all households worldwide spend more than 30% of their income on rent, and the global house-price-to-income ratio rose from 9.3 in 2010 to 11.2 in 2023 UNHabitat2026.

The lesson is to read SDG 11 as a dashboard with mixed signals, not "all bad" and not "all good." The pro-city thesis has empirical traction in some places and at some scales; the SDG 11 off-track verdict is also empirically grounded. The discipline's job is to hold both at once.

6. What does the discipline's vocabulary look like encoded into a planning document? — The Shenzhen TSP 2021–2035 as a worked example

The discipline's vocabulary becomes operational when it is encoded into a planning document. China's 国土空间规划 (Territorial Spatial Planning) reform is the contemporary case study the slide deck foregrounds, and the Shenzhen Territorial Spatial Master Plan (深圳市国土空间总体规划 2021–2035) is its worked municipal example ChinaTSP. The official plan map below is the canonical visual:

Caption: The four-colour legend is the canonical visual for "what does an urban-boundaries map actually look like?" Pink/salmon dominates the western and central districts (the original Special Economic zone); green concentrates in the eastern mountains and northern hills (the ecological backbone); yellow appears as scattered agricultural patches; light blue traces the marine boundary with Hong Kong SAR visible to the south. The official map is published by the Shenzhen Municipal Planning and Natural Resources Bureau (深圳市规划和自然资源局); precise map-printing metadata such as the 审图号 should be verified against the bureau's gazette before citation ChinaTSP.

The map is the instantiating document for an abstract framework: the 三区三线 (Three Zones, Three Control Lines) scheme, codified in the 2022 Ministry of Natural Resources (MNR) delineation circular ChinaTSP. The three zones are urban development (城镇开发), ecological protection (生态保护), and agricultural production (农业). The three control lines are the urban development boundary (城镇开发边界, a solid line), the ecological protection redline (生态保护红线), and the permanent basic farmland redline (永久基本农田红线). The schematic below visualises the abstract scheme:

The reform sits inside a five-stage evolution of China's planning system ChinaTSP. From 1949 to 1978, under the planned economy, spatial planning translated national economic plans into spatial arrangements. From 1978 to 1992, reform experimentation produced multi-plan coexistence (national land, urban-rural, land-use). From 1992 to 2010, the socialist-market-economy era produced an urban "growth machine," with land-finance reshaping central-local relations. From 2010 to 2018, overlapping mandates and the ecological-civilisation turn introduced the Major Function-Oriented Zoning Plan. Since 2018, the State Council Institutional Reform Plan established the Ministry of Natural Resources (MNR) and consolidated urban-rural planning into a unified territorial spatial planning system organised as 五级三类 — five administrative levels (central, provincial, municipal, county, township) crossed with three plan types (master, special, implementation). The Shenzhen TSP 2021–2035 belongs to this most recent stage.

A useful diagnostic lens for reading any such planning document is the cognition–relation–testing three-level framework developed in the 2026 MDPI Land paper that anchors the China thread ChinaTSP. At the cognitive level, you ask whether policy texts institutionalise goal articulation, value orientations, baseline boundaries, and explicit trade-off rules. At the relational level, you ask whether authority-responsibility allocation across central-local hierarchies, departments, and actors is translated into coordination mechanisms and linkage procedures. At the testing level, you ask whether land-use control, monitoring, feedback adjustment, and accountability incentives together form an auditable closed loop. Crucially, the three levels are framed as an iterative feedback loop, not a linear sequence.

The Shenzhen TSP map above is the cognitive level made visible: the four colours are the operational instantiation of the trade-off rules between urban growth, ecological protection, agricultural preservation, and marine boundaries. The next step — beyond what the map can show — is to read the planning document itself against the cognition-relation-testing framework and ask which level it is strongest and weakest at. That is the kind of critical, walking, data-literate habit the lecture is trying to cultivate.

So: is the city a triumph, or are cities stretched beyond what they can sustain? The discipline has not answered the question. It has, instead, given you the vocabulary to ask sharper versions of it. Walk a street this week. Look at the small blocks and the mixed uses. Then read the WUP 2025 number behind it. Then read the SDG 11 dashboard against it. Then read Harvey against Glaeser against Jacobs. The discipline is the argument between those four moves, and the city is what you make of it.

References

1. Jane Jacobs, The Death and Life of Great American Cities (Random House, 1961; Pelican reprint 1965 with subtitle "The Failure of Town Planning"). See Penguin Random House publisher page.
2. Xiangming Chen, Anthony M. Orum, and Krista E. Paulsen, Introduction to Cities: How Place and Space Shape Human Experience, 2nd ed. (Wiley-Blackwell, April 2018), ISBN 978-1-119-16772-3. See Wiley product page.
3. UN DESA Population Division, World Urbanization Prospects: The 2025 Revision (Summary of Results, 124 pp., released 18 November 2025; 22nd edition, supersedes WUP 2018). See UN WUP 2025 landing page.
4. Edward Glaeser, Triumph of the City: How Our Greatest Invention Makes Us Richer, Smarter, Greener, Healthier, and Happier (Penguin Press hardcover 10 Feb 2011, ISBN 978-1-59420-277-3; Penguin Books paperback 31 Jan 2012, ISBN 978-0-14-312054-4). See Penguin Random House publisher page.
5. David Harvey, "The Right to the City," International Journal of Urban and Regional Research 27(4):939–941, December 2003, DOI 10.1111/j.0309-1317.2003.00492.x. See IJURR article page.
6. UN-Habitat, SDG 11 Global Report 2026: Housing at the Centre of Sustainable Cities and Communities (108 pp., 2026); SDG 11 Key Facts and Messages companion (24 pp., 9 July 2026); UN Statistics Division, The Sustainable Development Goals Report 2026 — Goal 11 (online edition, 2026). See UN-Habitat SDG 11 Global Report page.
7. Hong Chenyuxuan, Zhang Zichun, Zhu Xigang, Zeng Peng, "Holism and Territorial Spatial Planning Reform in China: Evolutionary Challenges and Governance Measures Under Chinese-Style Modernization," Land 15(2):347, 20 February 2026, DOI 10.3390/land15020347.