The United States is the third most

populous country on Earth. Even

so, it comprises less than 5 percent

of the world’s population and

accounts for an even smaller

fraction of global population

increase. 

During the decade of the 1990s, the

population of the United States grew

by some 13 percent. This change is

five times the average percentage

increase of other industrialized

countries during the same period.

Though it has only about one-fourth

the total population of India, the

United States has more people ages

80 and over. At the same time, the

United States has more than twice

the total population of Nigeria but

fewer children under the age of 5.

Census 2000 improves our understanding

of the ways in which the U.S. population

is evolving as we enter the new millennium. It also underscores the commonalities, and a number of important differences, between the United States and

other national populations. Recognizing

the differences between U.S. population

size, growth, and structure and those of

other world regions and countries

strengthens our understanding of

America’s place in today’s world and the

relative opportunities, constraints, and

challenges we will face in coming years.

This brief, part of a series that analyzes

population and housing data collected

from Census 2000, compares the U.S.

population in 2000 with those of other

countries and major world regions, focusing on population size, growth, and agesex composition. It provides some explanation for major differences in population

size and structure among countries. It

also underscores differences in national

population growth between the United

States, other more developed countries

(MDCs), and the world’s less developed

countries (LDCs),1 and links these to the

same population dynamics underlying age

composition differences.

Population size and composition

together help explain global change

and national challenges.

With a total of 281 million people, the

United States had a larger population in

2000 than all countries except China and

India. However, the size of a country’s

total population tells only a small part of

its demographic story. A country’s population growth rate and its age-sex composition indicate the challenges it faces in

providing health care for its children and

elderly, providing education to its youth,

U S C E N S U S B U R E A U

Helping You Make Informed Decisions

U.S.Department of Commerce

Economics and Statistics Administration

U.S. CENSUS BUREAU

Issued February 2002

C2KBR/01-11

The United States in 

International Context: 2000

Census 2000 Brief

By 

Thomas M. McDevitt and

Patricia M. Rowe All modern censuses collect information on the age and sex composition

of population. Most countries take a

census and collect age-sex data once

every 10 years. This brief combines

age-sex data from Census 2000 with

figures prepared by the Census

Bureau for other countries to compare the population compositions of

the United States, other countries,

and world regions. 

1 More developed countries include all of North

America and Europe, as well as Japan, Australia, and

New Zealand. The remaining countries of the world are

considered less developed countries.
2 U.S. Census Bureau

providing employment opportunities for its young adults, and supporting its elderly population.

Figures 1 and 2 show the distribution of global population in 2000 —

where people lived — and that part

of growth during the 1990s that

was accounted for by a handful of

countries, as well as their contribution to change in the children

(under 15) and elderly (65 and over)

age groups.

Figure 1 shows the percentage of

global population in 2000 living in

the five most populous countries

and the remaining countries of the

world. The second and third bars

show where the world’s children

and elderly populations lived, again

focusing on the five countries

accounting for the largest shares of

these age groups globally. The

United States ranked third in terms

of total population size in 2000,

with just under 5 percent of world

population. It also accounted for

large shares of the world’s children

(ranking fourth among all countries

with 3 percent of the world’s under15 population) and elderly (ranking

third among countries with 8 percent of the total). 

The distribution of population of

specific age groups across countries — where the world’s children

live, or the world’s elderly, or any

other age-specific population —

depends entirely on the total population size of individual countries

and on the age composition of

each country. For example,

because of higher fertility in the

recent past, Pakistan and Indonesia

had larger proportions of their

population under age 15 than the

United States in 2000. However,

the United States’ overall larger

size offset the younger age distributions of Pakistan and Indonesia

so that each country accounted for

a roughly similar share of the

world’s under-15 population (Figure

1). Similarly, more developed countries such as the United States have

somewhat lower fertility and mortality than countries in Africa, Asia,

and Latin America, and consequently somewhat larger proportions of

their populations were elderly in

2000. Countries with the largest

shares of the world’s elderly included three of these MDCs — the

United States, Japan, and Russia —

plus China and India which,

because of their overall size,

account for large shares of the elderly globally.

During the 1990s, the United

States, along with India, China,

Nigeria, and Indonesia accounted

for nearly half of all global population increase (Figure 2). The importance of these countries to world

population change is attributable to

a combination of (1) their population size in 1990 and (2) their

respective rates of growth during

the decade. Each of these countries

is large in both absolute terms and

relative to other countries in their

region. The similarity in size of

shares of global population increase

of the United States, on the one

hand, and Nigeria and Indonesia,

both which have smaller populations than the United States, on the

other, is due to the much lower

growth rates of the United States in

comparison with Nigeria and

Indonesia. (From 1990 to 2000,

Indonesia’s population increased by

19 percent and Nigeria’s by 33 percent, compared with the United

States’ 13 percent.) The same effect

explains the similar proportions of

global population increase accountFigure 1.

Distribution of the World's Population: 2000

Source : U.S. Census Bureau, International Data Base; Census 2000 Summary File 1; United Nations, 

1999, World Population Prospects. The 1998 Revision, ST/ESA/SER.A/180, New York, for the age-sex 

distribution of some countries in 1990. 

Percent

Remaining 

world

China

India

United States

Indonesia

Brazil

(For information on confidentiality protection, nonsampling error, and 

definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Remaining 

world

India

China

Indonesia

United States

Pakistan

China

Remaining 

world

Russia

Japan

United States

India

0

10

20

30

40

50

60

70

80

90

100

 65 and over

population

 Under-15

population

Total

population
ed for by China and the slightly

smaller but more rapidly growing

India. The distribution of global

population increase is important

because it indicates those parts of

the world with the largest absolute

increases in needs for food, housing, social services such as health

care, and employment, as well as

the potential for regional and global

environmental impact.

At the turn of the millennium, populations are aging — median ages of

national populations are rising — in

every major world region. More

developed countries (MDCs) with

low fertility and low mortality are

contributing heavily to this process,

but so are some less developed

countries (LDCs), such as China,

which have seen their birth rates

fall dramatically over the past two

decades. China, Japan, Indonesia,

and the United States are four of

the five countries that contributed

most to the growth of the world’s

elderly population between 1990

and 2000 by virtue of their relatively low mortality and relatively large

overall populations (Figure 2, third

bar). 

At the other end of the age range,

the United States and other MDCs

contributed relatively little to the

growth of the world’s under-15 population during the past decade.

Ninety percent of the world’s children lived in LDCs in 2000, and

most of the increase in this age

group during the 1990s occurred in

Africa, Asia, and Latin America.

Five developing countries accounted for about 60 percent of the

growth of the world’s under-15 population during the decade (Figure 2,

second bar). The United States

ranked sixth among countries in

contributing to the growth of the

under-15 population during the

1990s (7 percent); no other MDC

was among the top 50 countries in

this respect.

The United States differs from

LDCs, but also from most

MDCs, in its growth.

For the past 50 years, the United

States and other MDCs have differed from the world’s LDCs in their

fertility, their mortality, and in their

overall growth. MDCs typically

have had lower fertility, mortality,

and population growth rates; LDCs

have had generally higher levels of

fertility, mortality, and population

growth. This broad generalization

is less true today than in the past.

Some demographic differences are

emerging between the United States

and other MDCs combined. The

U.S. contribution to total global

population change discussed earlier

partially reflects the fact that the

U.S. population is growing faster

than most MDCs: from 1990 to

2000 the U.S. population increased

by 13 percent compared with 

2.5 percent for other MDCs combined. As a result of its somewhat

higher fertility — women in the

United States give birth to more

than two children on average over

the course of their reproductive

lives, while women in most other

MDCs have lower fertility — and

substantial immigration, the United

States added more people to its

population than all other MDCs

combined during the decade.

Eleven MDCs in Eastern Europe and

the former Soviet Union actually

lost population during the decade

of the 1990s. The generally higher

rates of population growth characteristic of the less developed countries of Africa, Asia, and Latin

America during the 1990s and the

generally lower rates of growth

characteristic of MDCs are shown in

Figure 3.

U.S. Census Bureau 3

Figure 2.

Contribution to World Population Increase: 

1990 to 2000 

Source : U.S. Census Bureau, International Data Base; Census 2000 Summary File 1; 1990 Census of 

Population and Housing, General Population Characteristics, United States (1990 CP-1-1) ; United Nations, 

1999, World Population Prospects. The 1998 Revision, ST/ESA/SER.A/180, New York, for the age-sex 

distribution of some countries in 1990. 

Percent

Remaining 

world

China

India

United States

Indonesia

Nigeria

(For information on confidentiality protection, nonsampling error, and 

definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Remaining 

world

India

Nigeria

Ethiopia

Congo 

(Kinshasa)

Pakistan

China

Remaining 

world

Indonesia

Japan

United States

India

0

10

20

30

40

50

60

70

80

90

100

65 and over

population

Under-15

population

Total

population
4 U.S. Census Bureau Figure 3. Percent Change in Total Population: 1990 to 2000 Source: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1; 1990 Census of Population and Housing, General Population Characteristics, United States (1990 CP-1-1). (For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf) Percent 25 and over 15 to 24 10 to 14 0 to 9 Less than 0 (population decline)
U.S. Census Bureau 5

A closer look at the age-sex

structure of the United States

and other populations reveals

important differences and

similarities.

Table 1 summarizes the key age

and sex compositional differences

between the U.S. population and

those of major world regions. The

last two columns of the table show,

respectively, the percentage of each

regional population falling into a

specific age group and the percentage contributed by the United

States or a region to that age group

for the world as a whole. 

Notice that: 

• About 20 percent of world population, but over 40 percent of

the world’s elderly, lived in the

United States and other MDCs in

2000. 

• Relatively small percentages of

LDC regional populations were of

working age (ages 15 to 642 —

proportions ranged from 53 percent to 64 percent) compared

with the situation in more developed countries (66 percent for

the United States, 68 percent for

other MDCs) with the smallest

percentage being that of the

world’s least developed major

world region, Sub-Saharan Africa. 

• A greater number of elderly

women than men were living in

each region in 2000. In general,

the largest percentage differences were found in the United

States and other MDCs.

The U.S. population was older —

meaning it had larger proportions

of people in older age groups (ages

65 or older and 80 or older) — than

much of the rest of the world in

2000 (Table 1, column 4). However,

the United States also had a slightly

younger population than most other

developed countries for two reasons. First, U.S. fertility is slightly

higher than that of other MDCs, as

mentioned earlier. Second, about

10 million more people entered the

United States than left the country

during the 1990-2000 period,

adding to the young adult age

groups of our population. 

Which countries are

demographically “young” . . .

Countries differ in age structure as

a result of past fertility, mortality,

and migration. In particular, countries with a history of higher fertility

tend to have younger populations

than countries with a history of

lower fertility. The United States,

like other MDCs, has a history of

relatively low fertility. Consequently,

in 2000, it was among the lowest

third of countries (175th out of

224) in terms of percentage of population under age 15. Countries

with higher percentages of population under age 15 are heavily concentrated in Sub-Saharan Africa and

the Pacific and, to a lesser extent, in

other developing regions; countries

with lower percentages are other

MDCs.

. . . and which countries are

older?

Figure 4 shows the percentage of

national population ages 65 and

over. Countries with high percentages of elderly are essentially the

world’s MDCs — the United States,

Canada, the European countries,

Japan, Australia, and New Zealand —

and a small handful of other countries with a history of relatively low

fertility and mortality. The United

States was among the top third of

countries (ranking 41st out of 224)

on percentage of population ages 65

and over in 2000.

Age composition matters

because it is indicative of a

country’s support burden.

A useful way of comparing the age

compositions of different countries

is to look at the ratios of children,

of the elderly, or of both, to working-age population. Such ratios,

referred to as support ratios or

dependency ratios, are meant to

represent the average number of

dependents each working adult

must support in a population.3 In

2000, the U.S. population was heavily concentrated in the 15 to 64

year old population (Table 1 and

Figure 5), with about half as many

children and elderly as working-age

population. In both its age structure and dependency ratio, the

United States was similar to other

more developed countries and differed markedly from many developing countries in 2000 (Table 2 and

Figure 5). LDCs as a group had a

broadly based age structure reflecting a larger share of population

under age 15 (33 percent compared

with 21 percent for the United

States) and a smaller share at ages

65 and above (5 percent compared

with 12 percent for the United

States). 

Table 2 presents the child, elderly,

and total dependency ratios4 for the

United States, other more developed

countries, and the world’s developing regions in 2000. Most countries

had a larger child dependency ratio

2 While mean age at entry into the labor

force, mean age at retirement, and thus actual

labor force, or working ages vary from country

to country, the convention of ages 15 to 64 is

often used for international comparisons. 

3 The commonly used age dependency ratio

is the number of people ages under 15 and 65

and over per 100 people ages 15 to 64. A

dependency ratio of 50 means that there are

twice as many people ages 15 to 64 as under

15 and 65 and over. This ratio is sometimes

used as a surrogate for the economic dependency ratio, number of people not working per

100 people working in a population. The age

dependency ratio is often used because it eliminates differences in definition between countries.4 The child dependency ratio (number of

people under age 15 per 100 people ages 15 to

64) and elderly dependency ratio (number of

people ages 65 and over per 100 people ages

15 to 64) are also useful in better understanding the age composition of the population.
6 U.S. Census Bureau

Table 1.

The Population of the United States and Major World Regions by Selected Age

Groups: 2000

(For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Age and country or region

Population (In thousands) Percent of

Both sexes Male Female

Total population

of the region

or country

World population

in the specified

age group

Total

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,067,418 3,053,701 3,013,717 100.0 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 281,422 138,054 143,368 100.0 4.6

Other More Developed Countries. . . . . . . 909,710 440,216 469,494 100.0 15.0

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 656,682 327,320 329,362 100.0 10.8

Near East and North Africa . . . . . . . . . . . . 313,780 160,331 153,449 100.0 5.2

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 3,314,435 1,695,445 1,618,990 100.0 54.6

Latin America and the Caribbean. . . . . . . 518,301 256,579 261,721 100.0 8.5

Other Less Developed Countries . . . . . . . 73,089 35,756 37,332 100.0 1.2

Under-5

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 610,222 312,823 297,398 10.1 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 19,176 9,811 9,365 6.8 3.1

Other More Developed Countries. . . . . . . 46,929 24,073 22,857 5.2 7.7

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 110,883 55,910 54,973 16.9 18.2

Near East and North Africa . . . . . . . . . . . . 38,593 19,711 18,882 12.3 6.3

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 331,899 171,320 160,579 10.0 54.4

Latin America and the Caribbean. . . . . . . 55,354 28,240 27,113 10.7 9.1

Other Less Developed Countries . . . . . . . 7,388 3,759 3,629 10.1 1.2

Children (under-15)

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,819,689 933,370 886,320 30.0 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 60,253 30,854 29,399 21.4 3.3

Other More Developed Countries. . . . . . . 158,391 81,138 77,253 17.3 8.7

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 290,982 146,434 144,548 44.3 16.0

Near East and North Africa . . . . . . . . . . . . 111,957 57,127 54,830 35.7 6.2

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 1,009,435 521,690 487,745 30.5 55.5

Latin America and the Caribbean. . . . . . . 164,580 83,889 80,692 31.8 9.0

Other Less Developed Countries . . . . . . . 24,091 12,238 11,853 33.0 1.3

Working-age population (15-64)

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,829,791 1,937,461 1,892,330 63.1 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 186,177 92,790 93,387 66.2 4.9

Other More Developed Countries. . . . . . . 616,036 306,336 309,700 67.7 16.1

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 346,562 172,115 174,448 52.8 9.0

Near East and North Africa . . . . . . . . . . . . 188,308 96,898 91,410 60.0 4.9

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 2,122,749 1,087,005 1,035,744 64.0 55.4

Latin America and the Caribbean. . . . . . . 325,490 160,522 164,968 62.8 8.5

Other Less Developed Countries . . . . . . . 44,469 21,794 22,674 60.8 1.2

Elderly (65+)

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 417,938 182,870 235,068 6.9 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 34,992 14,410 20,582 12.4 8.4

Other More Developed Countries. . . . . . . 135,283 52,742 82,541 14.9 32.4

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 19,137 8,771 10,366 2.9 4.6

Near East and North Africa . . . . . . . . . . . . 13,515 6,305 7,210 4.3 3.2

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 182,251 86,750 95,501 5.5 43.6

Latin America and the Caribbean. . . . . . . 28,231 12,168 16,062 5.4 6.8

Other Less Developed Countries . . . . . . . 4,529 1,724 2,805 6.2 1.1

Oldest old (80+)

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70,172 25,113 45,059 1.2 100.0

United States . . . . . . . . . . . . . . . . . . . . . . . 9,185 3,062 6,123 3.3 13.1

Other More Developed Countries. . . . . . . 27,634 8,277 19,358 3.0 39.4

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . 2,215 967 1,247 0.3 3.2

Near East and North Africa . . . . . . . . . . . . 1,867 800 1,067 0.6 2.7

Asia and Oceania . . . . . . . . . . . . . . . . . . . . 23,811 10,024 13,787 0.7 33.9

Latin America and the Caribbean. . . . . . . 4,797 1,806 2,991 0.9 6.8

Other Less Developed Countries . . . . . . . 663 178 485 0.9 0.9

Note: Non-U.S. population figures are taken from the U.S. Census Bureau’s International Data Base but have been adjusted to April 1, 2000 to be

consistent with dating of Census 2000 figures. Asia and Oceania exclude Japan, Australia, and New Zealand (which are more developed countries).

Three Oceania countries (Cook Islands, Federated States of Micronesia, and Wallis and Futuna) are excluded because the Census Bureau has not

prepared estimates of the population of these countries by age and sex. The Other Less Developed Countries group includes Armenia, Azerbaijan,

Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The Other More Developed Countries group excludes the United States.

Source: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1.
Figure 4.

Percentage of Population Ages 65 and Older: 2000Source: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1.(For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Percent15 and over10 to 145 to 9Under 5

U.S. Census Bureau7
8 U.S. Census Bureau

Figure 5.

Percentage Distribution of Population by Age and Sex: 2000 

Sources: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1.

United States

Percent of total population

6543210

 0- 4

 5- 9

 10-14

 15-19

 20-24

 25-29

 30-34

 35-39

 40-44

 45-49

 50-54

 55-59

 60-64

 65-69

 70-74

 75-79

 80+

123456

Other more developed countries

6543210

 0- 4

 5- 9

 10-14

 15-19

 20-24

 25-29

 30-34

 35-39

 40-44

 45-49

 50-54

 55-59

 60-64

 65-69

 70-74

 75-79

 80+

123456

Less developed countries

6543210

 0- 4

 5- 9

 10-14

 15-19

 20-24

 25-29

 30-34

 35-39

 40-44

 45-49

 50-54

 55-59

 60-64

 65-69

 70-74

 75-79

 80+

123456

Male Female

Age

(For information on confidentiality protection, nonsampling error, and definitions, see 

www.census.gov/prod/cen2000/doc/sf1.pdf)

Elderly

Working age

Children
than elderly dependency ratio, and

this was uniformly true of the developing countries of Africa, Asia, and

Latin America. Developing countries

as a group had a larger total

dependency ratio and a much larger

child dependency ratio than the

United States, reflecting the greater

number of children being supported

by working-age adults in Africa,

Asia, and Latin America.

The United States differed less from

most other developed countries in

levels of child and elderly dependency. The average child dependency ratio for all other MDCs was 26

in 2000; the elderly dependency

ratio, 22. The U.S. child dependency

ratio of 32 was somewhat higher

than that of other MDCs, and our

elderly support ratio was slightly

smaller in 2000 because of

America’s higher fertility and the

volume of immigration into the

United States, as mentioned earlier.

The youngest and oldest

populations foretell the

future.

The distributions of the world’s children and its oldest old (population

ages 80 and above) indicate where

in the world the needs for children

and elderly health care services are

greatest in the current time period,

and where needs for schooling and

elderly support will be greatest in

the coming years. The United

States’ or any country’s age structure and its support ratios, together

with its national wealth, indicate the

extent to which it is likely to be

able to address those needs in the

current period. Countries with rapidly growing under-5 and oldest-old

populations are likely to face additional challenges in the decades

ahead. 

• Nearly 60 percent of the world’s

children under age 5 lived in just

ten countries in 2000 (Table 3).

The United States is the only

MDC among these countries; in

2000 about 3 percent of the

world’s under-5 population lived

U.S. Census Bureau 9

Table 2.

Dependency Ratios, the United States and Other World Regions: 2000

(For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Country or region Child Elderly Total

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 11 58

United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 19 51

Other More Developed Countries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 22 48

All Less Developed Countries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 8 61

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 6 89

Near East and North Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 7 67

Asia and Oceania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 9 56

Latin America and the Caribbean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 9 59

Other Less Developed Countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 10 64

Source: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1.

Table 3.

Top Ten Countries in Population Under Age 5 and Age 80 and Over: 2000

(For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Country

Population under age 5 Population 80 and older

Number

(In thousands)

Percent of

world total Country

Number

(In thousands)

Percent of

world total

India . . . . . . . . . . . . . . . . . . . 116,779 19.1 China . . . . . . . . . . . . . . . . . 11,823 16.8

China . . . . . . . . . . . . . . . . . . 99,643 16.3 United States. . . . . . . . . . 9,185 13.1

Indonesia. . . . . . . . . . . . . . . 24,071 3.9 India . . . . . . . . . . . . . . . . . . 6,110 8.7

Nigeria . . . . . . . . . . . . . . . . . 20,921 3.4 Japan . . . . . . . . . . . . . . . . . 4,621 6.6

Pakistan. . . . . . . . . . . . . . . . 20,539 3.4 Russia . . . . . . . . . . . . . . . . 2,953 4.2

United States . . . . . . . . . . 19,176 3.1 Germany . . . . . . . . . . . . . . 2,893 4.1

Brazil . . . . . . . . . . . . . . . . . . 16,453 2.7 United Kingdom . . . . . . . . 2,352 3.4

Bangladesh. . . . . . . . . . . . . 14,628 2.4 Italy. . . . . . . . . . . . . . . . . . . 2,291 3.3

Ethiopia . . . . . . . . . . . . . . . . 11,830 1.9 France . . . . . . . . . . . . . . . . 2,201 3.1

Mexico . . . . . . . . . . . . . . . . . 11,405 1.9 Spain . . . . . . . . . . . . . . . . . 1,461 2.1

Top ten countries. . . . . . . . 58.2 Top ten countries . . . . . . . 65.4

Source: U.S. Census Bureau, International Data Base; Census 2000 Summary File 1.
in the United States. A majority

of the world’s population under 5

lived in less developed countries;

over a third lived in India and

China, and another 20 percent

were found in the remaining

seven developing countries

shown in Table 3. 

• In contrast, 65 percent of the

world’s oldest old lived in ten

countries comprised primarily of

MDCs. The United States

accounted for 13 percent of the

world’s oldest old. China had the

largest percentage of the world’s

oldest old (almost 17 percent)

primarily because its overall population size dwarfs that of most

other countries. Except for the

world’s two largest countries, no

other LDCs made the top ten list

for the oldest old. 

Over the course of the next quarter

century (from 2000 to 2025), world

population is expected to increase

by 29 percent, with nearly all

growth occurring in less developed

countries; to grow older (rising

median age and larger proportions

of population at ages 80 and

above); and to become slightly less

male-dominant (a lower male-tofemale ratio5

) than in 2000. Census

Bureau projections indicate that:

• The U.S. population will be 

23 percent larger by 2025, compared with 2000.6 Excluding the

United States, MDCs as a group

are likely to see a decrease in

population of about 1 percent,

and the age distribution of this

group of countries will change

substantially. LDCs as a group

will grow by 35 percent over the

2000-2025 period.

• In 2000, there were about 101

men for every 100 women

worldwide. The ratio of men to

women was lower in the world’s

more developed regions (96 for

the United States and 94 for

other MDCs) than in LDCs (103).

Associated differences in numbers surviving become more pronounced in relatively low mortality, older populations such as in

the United States. By 2025, the

male-to-female ratio worldwide

and for LDCs will decline very

slightly as the world’s population

ages. There will be approximately equal numbers of men and

women globally and about 101

men per 100 women in the

world’s LDCs. Little change is

expected in the ratio of men to

women for the United States and

other MDCs.

• Between now and 2025, as fertility continues to decline and relatively large adult cohorts grow

older, the world’s population will

continue to “age,” resulting in a

higher proportion elderly and a

smaller proportion children. By

2025, the number of elderly will

nearly double, a percentage

increase about three times that

of the working-age population,

while the number of children

globally will be just 3 percent

larger than in 2000. Population

aging will occur in both MDCs

and LDCs. The United States is

expected to have nearly 80 percent more elderly than in 2000

but just 15 percent more working-age adults and 15 percent

more children. Other MDCs as a

group are expected to have a

smaller but still substantial

increase in elderly population 

(46 percent over 2000) combined

with sharp decreases in child and

working-age populations 

(17 percent and 7 percent,

respectively). LDCs should see

their elderly grow by 130 percent, or over twice as fast as the

growth of the elderly in more

developed countries, between

2000 and 2025. LDCs will experience an increase of 5 percent in

under-15 population and an

increase of 44 percent in working-age population. 

• As a result of these shifts in age

structure, the world’s elderly

dependency ratio will be about

50 percent higher in 2025 than

in 2000 (16 compared with 11

dependents per 100 workingage adults, Tables 4 and 2,

respectively) but global total

dependency will decline from

about 58 to 53. Elderly support

ratios will be higher in the United

States and other MDCs in 2025

(30 and 34, respectively, compared with 13 for the LDCs).

Over the coming quarter century,

as a result of the aging of MDC

populations, the historically higher total dependency ratios of less

developed regions will be

eclipsed by those of more developed countries. 

During the coming quarter century,

prevailing low fertility will account

for declining proportions of MDC

populations in the under-5 and

under-15 age groups and, in some

countries, for absolute declines in

the size of the under-5 population.

It also will account for the coming

decline in working-age population

in MDCs as a group. 

The shifting age structures of the

United States and other MDCs evident in the declining under-5 populations in the late 1990s mark the

advent of a demographic challenge

that will confront low-fertility countries during the coming decades.7

10 U.S. Census Bureau

5 Male-to-female ratio refers to the number

of people in a population who are male relative

to those who are female. 6 U.S. Census Bureau, Census 2000

Summary File 1; Projections of the Total

Resident Population by 5-Year Age Groups, and

Sex with Special Age Categories: Middle Series,

2025 to 2045 (NP-T3-F; January 13, 2000

Internet release).

7 United Nations, 2000, Replacement

Migration, ESA/P/WP/160, New York.
More industrialized nations as a

group will be forced to support a

growing elderly population even as

smaller cohorts of workers enter

the labor force. However, if present

trends continue, the impact of population aging is likely to be less

severe in the United States than in

other MDCs because immigration

and fertility both serve to replenish

our younger population age groups

to a greater extent than in other

MDCs. 

FOR MORE INFORMATION

For more information on U.S. population within the global context,

visit the U.S. Census Bureau’s 

Internet site at www.census.gov/

ipc/www/index.html. The recent

past, current status, and future of

global population are discussed in

the Census Bureau’s Global

Population Profile: 2000 (forthcoming 2002). The Census Bureau’s

most recent estimates of the size,

age-sex structure, growth, and

other demographic characteristics

of 227 countries and areas of the

world are available from the

International Data Base at 

www.census.gov/ipc/www/

idbnew.html.

Census 2000 data are available 

on the Internet via 

factfinder.census.gov and may be

purchased on DVD. Information on

other population and housing topics

is presented in the Census 2000

Brief series located on the U.S.

Census Bureau’s Web site at

www.census.gov/population/

www/cen2000/briefs.html. This

series presents information about

race, Hispanic origin, age, sex,

household type, housing tenure,

and other social, economic, and

housing characteristics.

For more information about Census

2000, including data products, call

our Customer Services Center at

301-763-INFO (4636) or e-mail 

webmaster@census.gov.

U.S. Census Bureau 11

Table 4.

Dependency Ratios, the United States and Other World Regions: 2025

(For information on confidentiality protection, nonsampling error, and definitions, see www.census.gov/prod/cen2000/doc/sf1.pdf)

Country or region Child Elderly Total

World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 16 53

United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 30 62

Other More Developed Countries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 34 57

All Less Developed Countries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 13 51

Sub-Saharan Africa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 6 72

Near East and North Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 11 53

Asia and Oceania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 15 47

Latin America and the Caribbean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 15 49

Other Less Developed Countries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 12 54

Source: U.S. Census Bureau, International Data Base.
U.S. Department of Commerce

Economics and Statistics Administration

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