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The United States Population in International Context:
2000 |
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Population
size and composition
United
States population growth
Age-sex
structure of the United States
Younger
countries
Older
countries
Age
compositions of different countries
Populations
age foretells the future
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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 age sex 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.
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Population size and composition together help explain
global change and national challenges. |
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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, 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.
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Figure 1.
Distribution of the World's population: 2000
Source: U.S. Census Bureau. International Data
Base; Census 2000 Summary File 1. |
Figure 2.
Contribution to World Population Increase: 1990 - 2000
Source: U.S. Census Bureau. International Data
Base; Census 2000 Summary File 1. |
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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 under-15
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 accounted
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.
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The United States differs from LDCs, but also from
most MDCs, in its growth. |
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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.
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Figure 3.
Percent Change in Total Population: 1990 to 2000
Source: U.S. Census Bureau. International
Data Base; Census 2000 Summary File 1.
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A closer look at the age-sex structure of the United
States and other populations reveals important differences and similarities |
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Table
1 (click link to see 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.
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Which countries are demographically "young"
. . . |
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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. |
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. . . and which countries are older? |
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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.
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Figure 4.
Percent of Population Ages 65 and Older: 2000
Source: U.S. Census Bureau. International
Data Base; Census 2000 Summary File 1.
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Age composition matters because it is indicative of
a country's support burden. |
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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
- click link to see 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 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.
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Table 2.
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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. |
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The youngest and oldest populations foretell the future.
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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 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.
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Table 3.
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• 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-to-female 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 working age
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.
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Table 4.
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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
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.
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Endnotes
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.
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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.
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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.
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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.
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5 Male-to-female ratio refers to the
number of people in a population who are male relative to those
who are female.
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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).
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7
United Nations, 2000, Replacement Migration, ESA/P/WP/160, New York.
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By Thomas M. McDevitt
and Patricia M. Rowe
Adapted from U.S. Census Bureau, The
United States in International Context: 2000, in Census
2000 Brief Series.
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