Urban growth in developing countries A review of

UrbanGrowthinDevelopingCountries:AReviewofCurrentTrendsandaCautionRegardingExistingForecastsBARNEYCOHEN*NationalResearchCouncil,Washington,DC,USASummary.—Thepurposeofthispaperistoclarifythenatureoftheon-goingurbantransitionindevelopingcountries,thequalityoftheavailabledata,andtheuncertaintyofexistingurbanforecasts.AlthoughtherecentlyreleasedUnitedNations’publicationWorldUrbanizationProspectsisaninvaluableresourceforthoseinterestedinstudyingurbanchange,thedatainthereportaresomewhatdeceptiveintheirapparentcompletenessandbeyondthenarrowconfinesoftechnicaldemographythereisagreatdealofmisunderstandingandmisreportingaboutwhatthesedatameanandhowtheyshouldbeinterpreted.Forexample,whilethescaleofurbanchangeisunprecedentedandthenatureanddirectionofurbanchangeismoredependentontheglobaleconomythaneverbefore,manyaspectsofthetraditionaldistinctionbetweenurbanandruralarebecomingredundant.Thispaperprovidesabroadoverviewoftheavailableevidenceonpatternsandtrendsinurbangrowthindevelopingcountries,highlightingregionaldifferenceswhereappropriate.Thepaperalsoexaminesthequalityofpasturbanpopulationprojectionsandfindsthattherehasbeenconsiderablediversityintheirqualitybygeographicregion,levelofdevelopment,andsizeofcountry.
2003ElsevierLtd.Allrightsreserved.Keywords—urbanization,citygrowth,Africa,Asia,LatinAmerica1.INTRODUCTIONS~aaoPauloisthelargesturbanagglomerationinBrazilandtheforemostindustrialcenterinSouthAmerica.Butuntilthe1880s,S~aaoPaulowasaminorcommercialcenter.In1890,whenRiodeJaneirohadapopulationofmorethanhalfamillion,thepopulationofS~aaoPaulowasonly65,000.Widespreadcoffeecultivationbroughtsuddenprosperitytotheregionandtransformeditfromanisolatedfrontiertoavibranteconomicregion.Bytheearly1900s,manufacturingbecameestablishedinS~aaoPauloandthepopulationgrewto240,000,dueinlargeparttoamassiveinfluxofimmigrantsfromvariouspartsofEurope.By1950,S~aaoPaulohadbecomethechiefmanufacturingcenterofBrazil.Today,theS~aaoPauloMetro-politanAreaaccountsforabouthalfofBrazil’stotalindustrialoutput.Notsurprisinglyperhaps,S~aaoPaulofacesmanyenvironmentandecologicalproblemsassociatedwithrapidindustrializationandpopulationgrowth.Morethan50%ofthepopulationlivesinsubstandardhousingandmanyresidentsdonothaveaccesstocleanwaterorsanitationservices.Airandnoisepol-lution,crime,overcrowding,andtrafficcon-gestionareallpervasiveproblems.Moreover,despiterapideconomicgrowth,thelocalecon-omyhasonlybeenabletoabsorbafractionofthegrowinglaborforcesothatunemploymentandunderemploymentremainpersistentprob-lems(Bruna,2000).Poorperformanceofthe–51,2004
2003ElsevierLtd.AllrightsreservedPrintedinGreatBritain0305-750X/$-seefrontmatterdoi:10.1016/j.worlddev.2003.04.008*AnearlierversionofthispaperwaspreparedfortheNationalResearchCouncil’sPanelonUrbanPopula-tionDynamics.TheauthorisindebtedtopanelmembersMarkMontgomery,RichardStren,CharlesBecker,EllenBrennan-Galvin,MichaelCohen,AlainDubres-son,GustavoGarza,TrudyHarpham,TerryMcGee,CarolineMoser,SaskiaSassen,DavidSatterthwaite,PravinVisaria,MichaelWhite,Yue-manYeung,andHollyReedforinnumerablediscussionsontheseissuesandtoAna-MariaIgnatforassistancepreparingthetablesandfigures.Foramoredetailedaccountofurbanpopulationdynamicsindevelopingcountries,seeNationalResearchCouncil(2003).Finalrevisionaccepted:16April2003.23Brazilianeconomyduringthe1990scoupledwiththedevaluationoftherealinJanuary1998havefurtherexacerbatedweaknessesinthelocaleconomy(Scott,2001a).Althoughuniqueinmanyways,manyele-mentsofS~aaoPaulo’sstoryarenotsouncom-mon.Inanincreasinglyurbanworld,almosthalftheworld’stotalpopulationandnearlythree-quartersofallWesternersliveinurbanareas.Atthebeginningofthe20thcentury,just16citiesintheworldcontainedatleastamil-lionpeople,thevastmajorityofwhichwereinindustriallyadvancedeconomies.Today,atthebeginningofthe21stcentury,therearearound400citiesaroundtheworldthatcontainoveramillionresidents,andaboutthree-quartersoftheseareinlow-andmiddle-incomecountries.AccordingtothelatestUnitedNations’pro-jections,virtuallyalloftheworld’spopulationgrowthoverthenext30yearswilloccurinurbanareas(seeFigure1).Inmanypartsoftheworld,urbanizationisbeingacceleratedby(andisaccelerating)anewglobaleconomythatisliterallychangingthefaceoftheplanet.Increasingly,urbangrowthisbeinginfluencedbycontinuedglobaleconomicintegrationandthestruggleforcountries––andindeedindividualcities––tobecompetitiveintheglobalmarketplace.Managingurbangrowthhasincreasedinbothscopeandcom-plexityandhasbecomeoneofthemostimportantchallengesofthe21stcentury.Whilethenotionofsustainableurbandevelopmentisonethatisnowfirmlyestab-lishedonboththescientificandpoliticalagendas,addressingtheseandotherurbanchallengeswill,ataminimum,requireaccurateandup-to-datedemographicdata.Manyquestionsemergefromtheabovediscussion:Whatarethecurrentratesofurbanizationandcitygrowtharoundtheworldandhowaretheserateschangingovertime?Howimportantwillmega-citiesbeinthe21stcenturyrelativetosmallormedium-sizedcities?Whatistherela-tivecontributionofrural–urbanmigration,natura