Slum
A slum is a group of individuals living under the same roof in an urban area who lack one or more of the following conditions: access to improved water supply, access to improved sanitation facilities, sufficient living area, durable housing structures, or secure tenure.[1] These settlements typically feature overcrowded, makeshift housing constructed from informal materials, inadequate infrastructure, and vulnerability to environmental hazards such as flooding or disease outbreaks due to poor waste management and sanitation.[2] As of 2022, approximately 1.12 billion people resided in slums worldwide, representing a reversal from prior declines and driven by rapid urban population growth outpacing housing and service provision in developing regions.[3] Slums predominantly emerge in low- and middle-income countries, particularly in sub-Saharan Africa, South Asia, and Latin America, where rural-urban migration for economic opportunities exceeds the supply of affordable, formal housing, often exacerbated by regulatory barriers, land scarcity, and insufficient investment in urban planning.[4] While slums harbor informal economic activities that sustain livelihoods, they are characterized by elevated risks of poverty perpetuation, health epidemics, and social instability, underscoring failures in governance and market responses to housing demand.[5]
Etymology and Definition
Historical Terminology
The term "slum" first appeared in early 19th-century British slang, with records from 1812 denoting a back room or compartment in a house, evolving to describe narrow, squalid alleyways by 1819. By 1825, "back slum" specifically referred to dirty back alleys in urban settings like London, inhabited by the poor and associated with vice. The word's origin remains uncertain, potentially linked to "slum" meaning sludge or mud, reflecting filthy conditions, or to "slumber" for sleeping places, though no definitive etymology exists.[6][7] In the mid-19th century, amid London's industrial expansion, "slum" shifted to encompass overcrowded, rundown districts such as those in the East End, marking a pejorative turn toward denoting dangerous, impoverished neighborhoods. Contemporary synonyms included "rookery," an 18th- and 19th-century term for labyrinthine tenements teeming with the poor, criminals, and prostitutes—evoking the dense nesting of rooks—and applied to notorious sites like the St. Giles rookery. "Shanty town" emerged around the same period in North American contexts, describing makeshift shacks for transient laborers, often tied to economic booms or depressions, contrasting with the more entrenched European usage.[7][8] The 20th century saw "slum" gain global traction through British colonial reports documenting urban poverty in empires, extending its application to non-European settings like Indian cities and African ports. This terminology persisted post-independence, with international bodies adopting "slum" to label durable, substandard settlements, distinguishing them from temporary squatter camps in analyses of housing deficits.[9][10]Modern Definitions and Criteria
The United Nations Human Settlements Programme (UN-Habitat) employs an operational definition of slums centered on five key deprivations experienced by households in urban settings: lack of access to improved water sources (defined as water from a piped supply, borehole, protected dug well, or packaged/rainwater sources); lack of access to improved sanitation facilities (such as flush toilets connected to sewers, septic tanks, or pit latrines with slabs); insufficient living area, measured as more than three persons sharing the same habitable room; non-durable housing structures (e.g., walls or roofs made of flimsy materials like metal sheets, plastic, or rudimentary wood lacking protection from elements); and insecure tenure (absence of legal protection against eviction or recognition of occupancy rights).[11][2] This framework, formalized for tracking Sustainable Development Goal Indicator 11.1.1 since 2015, prioritizes empirical indicators of physical and service deficits over subjective assessments of poverty or aesthetics, allowing for quantifiable measurement via household surveys and censuses.[11] National criteria often adapt these metrics but incorporate local legal or administrative thresholds, leading to variations. In India, the 2011 Census defines slums as contiguous settlements notified by government authorities as such, or unauthorized/older habitations with substandard structures and inadequate basic services (e.g., water, drainage, roads), or areas where at least 40% of households reside in poorly built dwellings lacking amenities like electricity or toilets; this approach emphasizes gazetted status alongside overcrowding exceeding three persons per room in some regional assessments.[12][13] In Brazil, the Instituto Brasileiro de Geografia e Estatística (IBGE) classifies favelas as subnormal agglomerations—irregularly occupied urban clusters with precarious, self-constructed housing (e.g., non-durable materials), high population density often surpassing three persons per room, and deficient infrastructure such as unpaved streets or shared water points—distinct from legal but low-quality housing by their origins in illegal land invasions.[14] These definitions highlight measurable standards like material durability (e.g., absence of concrete or brick) and overcrowding ratios, though they diverge on whether illegality or mere informality constitutes a core criterion. Debates persist regarding the scope of slum designations, particularly the tension between service-based informality and explicit illegality. UN-Habitat's criteria, while verifiable through deprivation counts, have been critiqued for overbreadth by including settlements with partial improvements or community-driven upgrades, potentially conflating transient service gaps with entrenched urban decay and inflating global estimates (e.g., from 827 million in 2018 to projections exceeding 1 billion by 2030) to support international aid frameworks without rigorous validation of permanence or causality.[15][16] Slums are distinctly urban phenomena, requiring proximity to city centers for economic viability, unlike rural poverty's dispersed agrarian deprivations or temporary camps (e.g., refugee or disaster sites), which lack enduring settlement patterns despite overlapping infrastructural shortfalls; this urban specificity underscores criteria focused on density-driven overcrowding and tenure insecurity amid rapid migration, excluding non-permanent or non-integrated habitations.[2]Historical Development
Pre-Industrial and Early Urban Slums
In ancient Rome, the Subura district, located between the Esquiline and Viminal hills, served as a densely populated area for the urban poor, featuring multi-story insulae—apartment blocks up to five or six floors high—that housed multiple families in narrow, poorly ventilated rooms lacking running water or adequate sanitation.[17] These structures, often constructed with timber and mudbrick, were prone to fires and collapses, contributing to hazardous living conditions amid narrow alleys congested with workshops, taverns, and markets.[18] Archaeological excavations, including those revealing sewer systems overwhelmed by waste, confirm the prevalence of overcrowding and filth, with population densities estimated at over 100,000 residents in a compact area by the 1st century BCE.[19] Medieval European cities exhibited similar slum-like enclaves within fortified walls that constrained expansion, exacerbated by guild monopolies on crafts and trades that limited housing construction to approved materials and locations, thereby inflating costs and densities for lower classes.[20] In Paris, areas akin to the later-documented Cour des Miracles—squalid courtyards housing beggars, thieves, and vagrants in makeshift hovels—emerged as early as the 12th century, characterized by open sewers, thatched roofs susceptible to plague, and social outcasts feigning disabilities for alms.[21] Guild controls, such as those enforced by the Hanseatic League in northern cities or Parisian craft associations, restricted non-guild members from building or settling freely, funneling the impoverished into peripheral or interstitial zones with rudimentary infrastructure.[22] Historical accounts from chroniclers like Froissart describe these districts as rife with mud-churned streets and overcrowding, where up to 20% of urban dwellers in cities like London or Florence lived in substandard timber-framed tenements by the 14th century.[23] In contrast, pre-colonial urban centers in Africa and Asia, such as Great Zimbabwe (peaking around 1450 CE) or Angkor (12th–15th centuries), showed limited evidence of concentrated slums due to communal land tenure systems that allowed flexible settlement patterns and organic expansion beyond rigid enclosures.[24] Decentralized governance and tribal land customs in sub-Saharan Africa, for instance, enabled migrants to claim peripheral plots for self-built dwellings, avoiding the density traps of European feudal restrictions.[25] Asian examples like medieval Kyoto featured dispersed artisan quarters with access to rice paddy commons, mitigating large-scale urban pauperization until colonial disruptions.[26] The precursors to industrial slums appeared in 18th-century Britain, where parliamentary enclosure acts—over 3,000 passed between 1760 and 1820—privatized roughly 21% of arable land, displacing an estimated 250,000 smallholders and laborers from common fields they had used for subsistence.[27] This rural exodus, driven by landlords consolidating holdings for sheep farming amid rising wool demand, funneled proletarianized peasants into nascent urban centers like Manchester and Birmingham, where makeshift housing clusters formed amid proto-industrial workshops.[28] By 1801, urban population shares had risen to 20% from 13% in 1700, straining rudimentary town planning inherited from guild-era constraints.[29]Industrial Era and 20th-Century Expansion
The Industrial Revolution, beginning in the late 18th century, accelerated rural-to-urban migration in Europe as workers sought factory employment, leading to the rapid formation of slums in burgeoning industrial centers like Manchester and London. In Manchester, the population surged from approximately 25,000 in 1773 to over 300,000 by 1851, driven by textile mills and cotton processing, resulting in overcrowded housing such as back-to-back terraces lacking sanitation and ventilation.[30] Friedrich Engels documented these conditions in 1845, describing Manchester's slums as labyrinthine districts with fever-ridden cellars and courts where multiple families shared inadequate facilities, fostering disease and poverty. Similar patterns emerged in London, where rapid industrialization concentrated working-class populations in areas like Bethnal Green and Whitechapel, characterized by high densities—often exceeding 150 persons per acre in court dwellings—and unsanitary conditions that contributed to cholera outbreaks in the 1830s and 1840s.[31] Charles Booth's comprehensive survey, Life and Labour of the People in London (published 1889–1903), quantified poverty across 442 square miles, classifying 30.7% of the population as living in poverty, with slums linked to structural factors including vagrancy laws under the Poor Law system that penalized unemployment and transiency, trapping the destitute in substandard housing.[32] Booth's color-coded maps highlighted "black" poverty zones in East London, where casual labor and irregular work perpetuated slum persistence despite industrial wages.[33] In the United States, parallel developments occurred with mass immigration and industrialization; by the late 19th century, New York City's tenements housed millions in squalid conditions, as exposed by Jacob Riis in How the Other Half Lives (1890), depicting overcrowding in areas like Mulberry Bend with up to 20 people per room and rampant tuberculosis.[34] Hell's Kitchen in Manhattan, a notorious Irish immigrant enclave, exemplified early 20th-century American slums with dilapidated wooden tenements, gang violence, and poverty persisting into the 1930s amid the Great Depression.[35] Precursor urban renewal efforts in the 1930s–1950s, including New Deal public housing initiatives and the 1949 Housing Act, aimed to clear such slums but often displaced residents without sufficient relocation support; in New York, projects razed blocks in Hell's Kitchen and adjacent areas, scattering low-income families into peripheral zones while failing to address root migration drivers.[36] Post-World War II, slum expansion extended globally through decolonization and economic reconstruction, as rural migrants flooded cities in Asia and Latin America seeking industrial jobs. In Mumbai, textile mills drew laborers from the 1920s onward, but post-1947 independence intensified influxes, overwhelming chawl housing and spawning unauthorized settlements by the 1950s, where mill workers and families endured makeshift dwellings amid booming urban populations.[37] This era's slum growth reflected universal patterns of industrialization-induced urbanization, independent of colonial legacies, with cities like Bombay mirroring European trajectories of density and deprivation.[38]Post-Colonial and Contemporary Growth
Following decolonization, slum proliferation intensified in Latin America and sub-Saharan Africa during the 1970s and 1980s, driven by the unraveling of import-substitution industrialization (ISI) models that prioritized urban manufacturing but neglected housing provision amid rising rural-urban migration.[39] ISI policies, implemented post-World War II, fostered urban job growth in protected industries, yet economic inefficiencies and the 1973 and 1979 oil crises triggered debt accumulation and policy shifts, accelerating informal settlement expansion as migrants sought informal employment without corresponding infrastructure.[40] In sub-Saharan Africa, urban bias in agricultural pricing and subsidies—evident from the 1970s onward—artificially depressed rural incomes, incentivizing mass exodus to cities where urban populations swelled under slum conditions, with over 60% of urban residents in such areas by 2005.[41] [42] These endogenous policy distortions, rather than mere colonial legacies, compounded during the 1980s structural adjustment programs under liberalization, which curtailed public investments while migration persisted due to persistent rural stagnation. Into the 2000s, Asia witnessed analogous surges tied to export-led industrialization outstripping housing supply; in Dhaka, Bangladesh, the urban population expanded from roughly 10 million in 2000 to over 15 million by 2010, propelled by garment sector booms that drew rural labor amid regulatory barriers to formal development.[43] [44] This pattern exemplified how rapid economic pull factors, unchecked by proactive land and building policies, perpetuated slum growth in liberalizing economies. Contemporary divergences highlight varying trajectories: China's state-orchestrated urbanization post-1990s reforms formalized migrant housing, drastically reducing informal settlements, whereas India's regulatory rigidities have sustained slum shares at approximately 30% of the urban population into the 2020s.[45] [46] World Bank assessments indicate these outcomes stem from differences in institutional capacity to align housing supply with endogenous migration pressures, with reversals in slum reduction evident in regulatory-heavy contexts.[47]Primary Causes
Rural-Urban Migration and Economic Pull Factors
Rural-urban migration constitutes a key mechanism fueling slum expansion, as individuals pursue higher expected earnings in cities despite the prospect of informal settlements. Migrants, often from surplus rural labor pools characterized by subsistence farming and stagnant incomes, are drawn by urban wage premiums that, even in unregulated sectors, exceed rural alternatives by factors of 2 to 3 times in developing economies.[48] This voluntary movement reflects rational decision-making based on perceived net gains in income and consumption potential, rather than coerced displacement.[49] In Kenya's Kibera slum, for example, rural migrants cite low agricultural productivity and limited rural opportunities as primary push factors, while urban job availability acts as the dominant pull, with surveys indicating economic motivations drive the majority of inflows.[50] This dynamic echoes the Lewis dual-sector model, wherein unlimited rural labor supply migrates to urban areas to capitalize on higher productivity, initially filling informal roles when formal absorption lags, thereby sustaining urban growth amid housing shortages.[51] Remittances from these migrants, often comprising 10-20% of urban earnings, bolster rural household welfare through investments in farming and education, creating a feedback loop that perpetuates migration flows.[52] Empirical analyses confirm that such migration yields net poverty reductions for entrants, as slum-based informal earnings enable escape from absolute rural deprivation, evidenced by improved caloric intake and asset accumulation relative to origins, though long-term urban entrapment risks arise from skill mismatches.[52][53] In Ghanaian cases, slum migrants reported household consumption gains of up to 50% post-relocation, underscoring the initial adaptive value of these moves despite substandard conditions.[52]