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WorldUrbanizationProspectsThe 2007 Revision

United NationsDepartment of Economic and Social Affairs (DESA) Population

Division - Population Estimates and Projections Section

www.unpopulation.org

Revision 1, 16 January 2008
http://www.unpopulation.org/http://www.unpopulation.org/http://www.unpopulation.org/


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Population Estimates and Projections SectionUnitedNationsDepartme

ntofEconomicandSocialAffairsPopulationDivision

World Urbanization Prospects: The 2007 Revision

1 An urbanizing world

2 Regional trends in urbanization

3 City growth / urban agglomerations

4 Projection methods

5 Methodological challenges


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1

An Urbanizing World

By the end of 2008 half of the worldspopulation

will live in urban areas.


4/35Population Estimates and Projections SectionU

nitedNationsDepartme


Population

(millions)

Global rural and urban population, 1950-2050 1

6,500

6,000

5,500

Urban population

Rural population

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

500

0

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

Source: UN Population Division/DESA, World Urbanization Prospects: The 2007 Revision, CD-Rom, 2008.


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2,500,001to 10,000,000

Lessthan2,500,001

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Population density in Europe, 2000 1

Source: IIASA, ERD Project


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ntofEconomicandS

ocialAffairsPopulationDivision

2Regional Trends of Urbanization

Developing regions, particularly in Africa and Asia, will

contribute the lionsshare to the growth ofthe worldwide urban population.


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Source: UN Population Division/DESA, World Urbanization Prospects: The 2007 Revision, CD-Rom, 2008.Population Estimates and Projections SectionU

nitedNationsDepartme

ntofEconomicandS

ocialAffairsPopulat

ionDivision

Population(millions)

Rural and urban population by development region, 1950-2050 2

5,500

5,000

4,500

4,000

More developed regions, urban population

Less developed regions, urban population

More developed regions, rural population

Less developed regions, rural population

3,500

3,000

2,500

2,000

1,500

1,000

500

0

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050


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Africa Asia Europe Latin America and

the Caribbean

Northern America Oceania


n

itedNationsDepartme

ntofEconomicandS

ocialAffairsPopulat

ionDivision

P

opulationlivinginurbana

reas

(percentage)

Percentage of population living in urban areas by geographical regions 2

100

90

80

70

1950 1975 2007 2050

84

72

8990

81

78

7476

72 71

66 66

62

60

64

61 62

51

50

4141

4039

3026

24

20 15 17

10

0


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Africa Asia Europe Latin America and

the Caribbean

Northern America Oceania


n

itedNationsDepartme

ntofEconomicandS

ocialAffairsPopulat

ionDivision

P

opulationlivinginurbana

reas

(percentage)

Percentage of population living in urban areas by geographical regions 2

100

90

80

70

1950 1975 2007 2050

84

72

8990

81

78

7476

72 71

66 66

62

60

64

61 62

51

50

4141

4039

3026

24

20 15 17

10

0

C t ib ti f l d b l ti th t t t l l ti th


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Source: UN Population Division/DESA, World Urbanization Prospects: The 2007 Revision, CD-Rom, 2008.Population Estimates and Projections SectionUn

itedNationsDepartme

ntofEconomicandS


Contributiontototalpop

ulationgrowth(percentage

)

Contribution of rural and urban population growth to total population growth2

by development region

100%

90%

80%

70%

50 47 4842

5452

3935 34

613

2217

28

60%

50%

40%

30%

27 3133

31 35

47 5256 59

7276

66

88 9881 110

124138

156179

20%

10% 22 22 1915 13 11 9 8

7 6 7 6 6 6 6 6 6 6 6 5

0%

-10%

-1 -2 -3

-4 -3-2

-1 -1 -1 -1 -1 -2 -3 -4-5 -6 -7 -7

-4

-17

-8 -9

-20%

-30-44

-61-84

-30%

-40%

1950-

19551955-

19601960-

19651965-

19701970-

19751975-

19801980-

19851985-

19901990-

19951995-

20002000-

20052005-

20102010-

20152015-

20202020-

20252025-

20302030-

20352035-

20402040-

20452045-

2050

More developed regions, urban population Less developed regions, urban population

More developed regions, rural population Less developed regions, rural population

, , -


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Q_

0

0cQ Population Average annual rate of change(I)

:::J

0.

(millions) (percentage)

0 Major area 1950 1975 2007 2025 2050 1950-1975 1975-2007 2007-2025 2025-20

U..._)

(I)

Urban population

Africa 33 107 373 658 1234 4.76 3.90 3.15 2.

:t:: Asia 237 574 1645 2440 3486 3.54 3.29 2.19 1.

(I) Europe 281 444 528 545 557 1.84 0.54 0.18 0.

0 LatinAmerica and the Caribbean 69 198 448 575 683 4.21 2.55 138 0.

(j)

Northern America 110 180 275 337 401 1.98 1.33 1.11 0.D

cOceania 8 15 24 30 37 2.60 1.44 1.17 0.

g

E0 Rural populationc0

Africa 192 309 592 736 764 1.92 2.03 1.21 0.w

Asia 1174 1820 2384 2339 1780 175 0.84 ..0.11 -1.0

c Europe 267 232 204 170 107 ..0.57..0.41 -1.00 -1.

ELatinAmerica and the Caribbean 98 126 124 113 87 1.01 ..0.06 ..0.50 -1.

t Northern America 62 64 63 56 44 0.11 ..0.02 ..0.65 -1.0.

Oceania 5 6 10 12 11 0.88 160 0.78 ..0.0U)

c0

(i5

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Un

itedNationsDepartme

ntofEconomicandS


3City Growth / Urban Agglomerations

Half of the worldsurban population is living in

urban settlements with fewer than500,000 inhabitants.

Population Estimates and Projections Section

by size class of urban settlement 1975 2007 and 2025


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-

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Un

itedNationsDepartmentofEconomicandS


Number of urban agglomerations by size class of settlement 3

600

500

Number of urban agglomerations

500,000 to 1 million.

Less developed regions

More developed regions

600

500


1 to 5 million.


More developed regions


5 million and more.80


70 More developed regions

60

400

300

200

100

136

340

419

400

300

200

92100

282

50

58423

40

30 37

20

1010

102 122132

71100 103

17

812

1975 2007 2025 1975 2007 2025 1975 2007 2025

Source: UN Population Division/DESA, World Urbanization Prospects: The 2007 Revision, CD-Rom, 2008.Population Estimates and Projections Section

c


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pation

ofurbanagglo

merationswith10

million

inhabitants

ormore

Populati

on

(millions) of change (percentage)

Urban agglomeration 1975 2007 2025 1975-2007 2007-2025

Tokyo,Japan 26.6 35.7 36.4 0.92 0.11

New York-Newark,USA 15.9 19.0 20.6 0.57 0.44

Ciudadde Mexico (Mexico City), Mexico 10.7 19.0 21.0 1.80 0.55

Mumbai (Bombay), India 7.1 19.0 26.4 3.08 1.83

So Paulo, Brazil 9.6 18.8 21.4 2.10 0.71

Delhi, India 4.4 15.9 22.5 4.00 1.92

Shanghai,China 7.3 15.0 19.4 2.24 1.44

Kolkata (Calcutta), India 7.9 14.8 20.6 1.96 1.83

Dhaka, Bangladesh 2.2 13.5 22.0 5.64 2.72

BuenosAires,Argentina 8.7 12.8 13.8 1.19 0.41

Los Angeles-LongBeach-Santa Ana,USA 8.9 12.5 13.7 1.05 0.50

Karachi,Pakistan 4.0 12.1 19.1 3.48 2.52

AI-Qahirah (Cairo), Egypt 6.4 11.9 15.6 1.91 1.49

Riode Janeiro,Brazil 7.6 11.7 13.4 1.38 0.74

Osaka-Kobe, Japan 9.8 11.3 11.4 0.43 0.04

Beijing, China 6.0 11.1 14.5 1.91 1.50

Manila, Philippines 5.0 11.1 14.8 2.49 1.60

Moskva (Moscow), RussianFederation 7.6 10.5 10.5 0.99 0.04Istanbul,Turkey 3.6 10.1 12.1 3.21 1.03

Note: lkbenagglomerations areorderedaccordingto theirpopuletion sizein2007.


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Population Estimates and Projections SectionUn



4Projection Methods

PercentageUrban

Cities / Urban Agglomerations

P j i h d U b l i (1) 4


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ocialAffairsPopula

tionDivision

Projection methods: Urban population (1) 4

Census 1(for instance: 1970)Urban-rural Ratio

Census 2(for instance: 1980)Urban-rural Ratio

Growth rate of the

urban-rural ratio

Difference between growth rate

of urban and rural population

Step 1: The URR is the basis for interpolation and extrapolation of the

urban population. The projection uses the most recent urban-rural growth

difference in a logistic equation. The proportion urban reaches its

maximum growth rate when the proportion urban is 50% and declines to its

asymptotic value of zero when the proportion urban is 100%.

P j ti th d U b l ti (2) 4


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ocialAffairsPopula

tionDivision

Projection methods: Urban population (2) 4

Normally, an extrapolation based on a simple logistic curve would imply

that the urban-rural growth difference remains constant over the projection

period. Empirical evidence shows that this is unrealistic.

Step 2: Global Norm

A simple model is used to reduce the value of the urban-rural growth

difference by calculating a hypothetical urban-rural growth difference (hrur)

according to the following formula:

Hrur = 0.037623-0.02604 PU (t0); PU(t0) is the proportion urban at the time of the initial census

Essentially, this means that with increasing (initial) urbanization, the value

of the hypothetical urban-rural growth difference (hrur) decreases.

In other words:

With growing urbanization the urbanization process slows down!

4


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ocialAffairsPopula

tionDivision

RUR

(growthrateoftheurban-ruralratio)

-.

05

0

.05

.1

.15

.2

Projection methods for urban population 4Using the Global Norm: Growth rate of the urban-rural ratio versus

proportion urban for countries with a population of more than 2 million

1950-2007 observations

< 1950 observations

hrur (WUP1996-WUP2007)

robust reg (1950-2007)

All years (including < 2 m.)

0 .2 .4 .6 .8 1PU (proportion urban)

Source: UN Population Division/DESA, World Urbanization Prospects: The 2007 Revision, CD-Rom, 2008.


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Population Estimates and Projections SectionUnitedNationsDepartm

entofEconomicandSocialAffairsPopula

tionDivision

5

Challenges

Challenges in estimating and projecting city populations 5


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tionDivision

Challenges in estimating and projecting city populations 5

Practical challenges

City names in foreign languages can be easily mixed up (Chinese)

Large amount of data (6000+ cities) in time-series

Methodological challenges

Definitions change from country to country

Definitions change over time (no consistency in time-series)

City boundaries are not drawn consistently (some cities include large

rural areas, others dont)

Neighboring cities may merge into one urban agglomeration

Small cities / villages may become huge cities due to special

development measures (Shenzhen, airport cities)

Reclassification of settlements (from village to town to city)


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Challenges: Distribution of countries according to the 5


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tionDivision


criteria used in defining urban areas (2005 Revision)

CriterionAdministrativeEconomicPopulation size/density

Sole use

Used in

conjunctionwith

other criteria

Percentage

according to

sole use

Percentageaccording to use

in conjunction

with other criteria81 126 35.5 55.3- 29 - 12.7

59 112 25.9 49.1Urban characteristics 4 26 1.8 11.4Administrative and population 13 - 5.7 -

Administrative and urban characteristics 5 - 2.2 -

Economic and population 5 - 2.2 -Population and urban characteristics 7 - 3.1 -Administrative, economic and population size 18 - 7.9 -

Administrative, urban characteristics and population 4 - 1.8 -

Economic, population and urban characteristics 1 - 0.4 -Administrative, economic, population size and urban characteristics 5 - 2.2 -

Entire population 6 6 2.6 2.6No urban population 2 2 0.9 0.9No definition 18 18 7.9 7.9

Total number of countries or areas 228 228 100.0 -



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tionDivision

Challenges: Distribution of countries according to the

criteria used in defining city populations (2005 Revision)

Criterion Sole use

Used in

conjunction with

other criteria

City proper 109 123

Urban agglomeration 87 103

Metropolitan area 12 21

Capital is urban agglomeration; other cities are city

proper, urban agglomerations or metropolitan areas8 0

Capital is city proper; other cities are city proper, urban

agglomerations or metropolitan areas3 0

Capital is metropolitan area; other cities are city proper,

urban agglomerations or metropolitan areas7 0

Not defined 2 4

Total number of countries or areas 228

World Urbanization Prospects: Publications


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tionDivision

World Urbanization Prospects: Publications

Report, including key findings, analytical chapters,

and data tables

CD-ROM with detailed data tables (EXCEL files)

Online-data on Web site (www.unpopulation.org)

Wall Charts


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Population Estimates and Projections SectionU

nitedNationsDepartm


tionDivision

Thank You !

United NationsDepartment of Economic and Social Affairs (DESA) Population Division

- Population and Estimates and Projection Section

www.unpopulation.org

Projection methods: City population (1) 4
http://www.unpopulation.org/http://www.unpopulation.org/


34/35


nitedNationsDepartm


tionDivision

Projection methods: City population (1)

Census 1(for instance: 1970)

Census 2(for instance: 1980)

City growth minus

urban growth

City-urban growthdifference RCU

The projection of city populations is similar to the projection of urban

populations:

Step 1: The city-urban growth difference (RCU) is the difference betweenthe rate of city population growth and the rate of total urban population

growth. A logistic regression is used to project this city-urban growth

difference.

Projection methods: City population (2) 4


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nitedNationsDepartm

entofEconomicand

SocialAffairsPopulationDivision

Projection methods: City population (2)

Normally, an extrapolation based on a simple logistic curve would imply

that the city-urban growth difference remains constant over the projection

period. Empirical evidence shows that this is unrealistic.

Step 2: Dampening of city growth

A simple model is used to reduce the value of the city-urban growth

difference by using a model that was calibrated on empirical data for

dampening city growth.

Essentially, this means that with increasing (initial) city size, the value ofthe projected city-urban growth difference (hrcu) decreases.

In other words:

Larger cities grow slower!

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