_________________________________________________________ 

Methodology and Assumptions for the Population 

Projections of the United States: 

1999 to 2100 

Population Division Working Paper No. 38 

Frederick W. Hollmann, 

Tammany J. Mulder, 

and Jeffrey E. Kallan 

Population Projections Branch 

Population Division 

U.S. Census Bureau 

Department of Commerce 

Washington, D.C. 20233 

(301) 457-2428 

www.census.gov 

Issued January 13, 2000 
U.S. National Projections 1 

ABSTRACT 

This working paper discusses the methodology and assumptions used to develop the recently released 

projections of the population of the United States from 1999 to 2100. The new series includes projections 

of the population by single year of age, sex, race, Hispanic origin, and nativity. While the basic 

methodology used to produce these projections is the same as in earlier Census Bureau national population 

projections, there have been changes, in both the time horizon and reference dates of the projections, as well 

as in the specific methods used to estimate population change. The extension of the series to 2100 carries 

the projections 20 years further into the future than any series previously issued by the Census Bureau. 

For the first time, projection results include a break on nativity, defined dichotomously by the presence or 

absence of U.S. citizenship at birth, as well as its cross-classification with other variables. Also new with 

this series is the projection to quarterly reference dates, allowing users to view the national population 

seasonally, or simply to select annual reference dates other than July 1. In addition, international migration 

in the new series is allowed to vary over time, remaining somewhat lower than the constant value in the 

previous series for the first two decades of the century, but reaching considerably higher levels than in the 

previous one after 2020. Fertility rates in both models are allowed to change very little over time. 

However, fertility rates by race and Hispanic origin are allowed to converge in the new middle series, 

whereas in the previous middle series they remained constant within race and origin category. Finally, the 

new mortality assumptions show more improvement in life expectancy for all racial and Hispanic origin 

groups, except the non-Hispanic White population, than did the assumptions of the previous projection 

series. 

ACKNOWLEDGMENTS 

This report was prepared under the general direction of Gregory Spencer, Chief of the Population 

Projections Branch. Statistical assistance was provided by Elizabeth Caffrey and Mary Jane Slagle. Signe 

Wetrogan, Assistant Division Chief for Population Estimates and Projections, provided overall direction. 

Professional consultation was provided by Gregory Spencer, Martin O’Connell, Scott Boggess, and Ching 

Li Wang. 

* This paper reports the results of research and analysis undertaken by Census Bureau staff. It has undergone a 

more limited review than official Census Bureau publications. This report is released to inform interested parties 

of research and to encourage discussion. 
U.S. National Projections 2 

CONTENTS Page
 

INTRODUCTION ...................................................................................................................................... 3 

THE METHOD OF PROJECTING THE POPULATION .............................................................................
 4 

Base Population and Base Series ..................................................................................................
 5
 

The Cohort-Component Method ...................................................................................................
 5
 

The Inflation-Deflation Method ....................................................................................................
 6
 

Derivation of Births, Deaths, and Foreign-Born Emigration from Rates .......................................
 7
 

Reflecting Uncertainty of Assumptions Through High and Low Variants ......................................
 8
 

ASSUMPTIONS FOR THE COMPONENTS OF CHANGE ....................................................................... 8
 

Short-term Fertility Assumptions 

Long-term Fertility Assumptions 

Long-term Assumptions for Fertility by Race and Hispanic Origin
 

Methodology 

Mortality Rates by Hispanic Origin
 

Problems With Race and Hispanic Origin Mortality Rates 

Old-age Mortality Rates 

Fertility ....................................................................................................................................... 8
 

Assumptions and Methodology ..................................................................................... 9
 

Low and High Fertility Assumptions ............................................................................ 11
 

Mortality .................................................................................................................................... 11
 

Assumptions and Methodology ..................................................................................... 12
 

Low and High Mortality Assumptions .......................................................................... 13
 

Two Sets of Base Mortality Rates: General Issues ........................................................ 14
 

Base Mortality Rates: Detailed Construction ................................................................ 14
 

International Migration ............................................................................................................... 15
 

Assumptions and Methodology .................................................................................... 16
 

Projection of the Level of In-Migration: Middle Series, 1999 to 2020 ........................... 17
 

Projection of the Level of In-Migration: Middle Series, 2021 to 2100 ........................... 18
 

Migration to the U.S. by Race and Hispanic Origin ...................................................... 19
 

Low and High International Migration Assumptions .................................................... 19
 

Projection of the Emigration of Legal U.S. Residents ................................................... 21
 

Low and High Emigration Assumptions ........................................................................ 21
 

Net Migration of U.S. Citizens ..................................................................................... 22
 

SUMMARY .............................................................................................................................................. 22
 

DETAILED TABLES 

Table A. Comparisons of Total Population, Present Series with 1994-Based Projections ............................
 24
 

Table B. Projected Total Fertility Rates by Race and Hispanic Origin, 1999 to 2100 ..................................
 25
 

Table C. Projected Life Expectancy at Birth by Race and Hispanic Origin, 1999 to 2100 ...........................
 26
 

Table D. Projected Migration by Race and Hispanic Origin, 1999 to 2100 .................................................
 27
 

Table E. Major Components of Net International Migration to the United States, 1991 to 2100 .................
 28
 

Table F. Population and Dependency Ratios per 100 Persons, Four Series, 1990 to 2100 ...........................
 29
 

Table G. Standardized Rates of Foreign-Born Emigration, 1991 to 2100 ....................................................
 30 

U.S. Census Bureau January 2000 
 

U.S. National Projections 3 

INTRODUCTION 

This working paper discusses the methodology 

and assumptions used to develop the recently 

released projections of the population of the 

United States from 1999 to 2100.1 The new 

series includes projections of the population by 

single year of age, sex, race, Hispanic origin, and 

nativity.2 While the basic methodology used to 

produce these projections is the same as in earlier 

Census Bureau national population projections, 

there have been changes, in both the time horizon 

and reference dates of the projections, as well as 

in the specific methods used to estimate 

population change. The extension of the series to 

2100 carries the projections 20 years further into 

the future than any series previously issued by 

the Census Bureau. For the first time, projection 

results include a break on nativity, defined 

dichotomously by the presence or absence of 

U.S. citizenship at birth, as well as its crossclassification with other variables. Also new 

with this series is the projection to quarterly 

reference dates, allowing users to view the 

national population seasonally, or simply to 

select annual reference dates other than July 1. In 

addition, international migration in the new series 

is allowed to vary over time, remaining somewhat 

lower than the constant value in the previous 

series for the first two decades of the century, but 

reaching considerably higher levels than in the 

previous one after 2020. Fertility rates in both 

models are allowed to change very little over 

time. However, fertility rates by race and 

Hispanic origin are allowed to converge in the 

new middle series, whereas in the previous 

middle series they remained constant within race 

and origin category.3 Finally, the new mortality 

1 At the time of release for this report, the results of these 

projections are located on the Census Bureau site of the Worldwide 

Web. U.S. Census Bureau; “National Population Projections;” 

<http://www.census.gov/population /www/projections/natproj.html> 

2 The information on the Hispanic population shown in 

this report was collected in the 50 States and the District of Columbia 

and, therefore, does not include residents of Puerto Rico. 

3 People of Hispanic origin may be of any race. 

assumptions show more improvement in life 

expectancy for all racial and Hispanic origin 

groups, except the non-Hispanic White 

population, than did the assumptions of the 

previous projection series. 

Aside from these changes, the basic structure of 

the product closely resembles previous Census 

Bureau projections. Race consists of four 

categories; 1) White, 2) Black, 3) American 

Indian, Eskimo, and Aleut, 4) Asian and Pacific 

Islander (API). Hispanic origin is dichotomous: 

the two categories are Hispanic and nonHispanic. All race and Hispanic origin detail 

incorporates the full distribution of eight crosscategories. As in previous projections, we have 

provided alternate series, defined by alternative 

assumptions on the three major determinants of 

population change, fertility, mortality, and 

migration. However, the interpretation of “low” 

and “high” assumptions has changed somewhat 

with respect to previous projections. In the 

present series, the extreme assumptions are 

presented primarily with the purpose of 

illustrating a degree of uncertainty around the 

central series. They should not be interpreted as 

alternative scenarios to be adopted on their face 

value, as they are not intended to be probable 

developments. 

The results of the new projections are not 

substantially different from those of the last 

series issued by the Census Bureau, when the 

comparison is made across matching dates.4 

Both middle series show the national population 

growing at a large fraction of one percent per 

year until 2050. Both series show the rate of 

growth declining over time, from approximately 

0.9 percent per year in 1999 to about 0.7 percent 

per year around 2050. These results are shown 

in Table A. The lack of major difference in the 

population results for the middle series between 

4 Jennifer Cheeseman Day, U.S. Census Bureau, 

Population Projections of the United States by Age, Sex, Race, and 

Hispanic Origin: 1995 to 2050, Current Population Reports, P25­

1130, U.S. Government Printing Office, Washington, District of 

Columbia, 1996. 

U.S. Census Bureau January 2000 
U.S. National Projections 4 

the new and old projections can be explained in 

large part by the deterministic nature of the age 

distribution of the base population, and the 

predictability of its aging over time. This initial 

age distribution represents essential information 

that is conveyed to the projected series. The 

means of its conveyance is the cohort component 

method, discussed in the section that follows. 

THE METHOD OF PROJECTING THE 

POPULATION 

The method used to produce projections of the 

United States population for future reference 

dates from a current base population reflects 

three fundamental principles. 

1) The projections are demographic. Future 

populations are derived from a base population 

through the projection of population change by 

its major demographic components, births, 

deaths, and migration. 

2) The projection of the demographic components 

of change is driven by the composition of the 

population by age, sex, race, Hispanic origin, and 

nativity, and the way these variables determine 

the propensity to bear children, die, and migrate 

to or from the United States. 

3) The definition of the population with respect 

to who is included and the characteristics of 

included people remains the same throughout the 

projection period. We refer to these definitions 

collectively throughout the work as the 

“population universe.” This concept embraces 

such issues as the inclusion or exclusion of 

people uncounted by a census, the rule defining 

residency in the United States, and the way we 

classify people by age, race, and Hispanic origin. 

The population universe for these projections is 

defined primarily by the 1990 census, albeit with 

some modifications. 

The first two principles mandate the use of 

“cohort component” methodology in projecting 

the population. Under this methodology, 

knowledge of the age and sex composition of the 

population at any point in time is fundamental to 

the projection of the population. Knowing the 

age-sex distribution at one date allows us to 

impute the age-sex distribution of those still alive 

at later dates, since sex does not change while 

age advances with the passage of time. This 

knowledge also allows the projection of 

demographic behaviors such as fertility, 

mortality, and the propensity to migrate, 

differentiated by age. Thus, current age-sex 

distribution influences future age-sex distribution 

through the components of change, as well as the 

aging of people over time. 

To comply with the second principle described 

above, standard cohort component methodology 

is applied to each racial and Hispanic origin 

category as if they were separate populations. 

Race and Hispanic origin are chosen because 

they are reflected in a wide range of 

administrative data in the United States, and 

because their categories are distinct with respect 

to rates of fertility and mortality. Nativity, 

defined by citizenship at birth, is used to 

distinguish rates of emigration from the United 

States. The foreign-born population is also 

projected separately, but without births, since 

children born within the United States are U.S. 

citizens at birth (native) by United States law. 

The third principle, preservation of the 

population universe, imposes the need for a 

special adaptation of cohort component 

methodology. The population universe for these 

projections is defined by the decennial census of 

April 1, 1990, with some adaptations. In certain 

critical regards, the distribution of this 

population by age, sex, race, and Hispanic origin 

does not submit well to projection by the cohort 

component method. It is characterized by a 

pattern of underenumeration highly differentiated 

by age, as well as some misreporting of age, and 

a distribution by race and Hispanic origin 

substantially different from what appears in other 

administrative data sources. In order to preserve 

these irregularities of the age detail in the 

U.S. Census Bureau January 2000 
U.S. National Projections 5 

projected population while maintaining the 

applicability of the cohort component method, we 

apply the standard method to a synthetic base 

population with characteristics “friendly” to the 

method. We then adapt the resulting projections 

back to the actual base population universe. This 

process is known as “inflation-deflation.” The 

following sections discuss this modified cohort 

component methodology. 

Base Population and Base Series 

The current series of population projections are 

“launched” from an estimated resident population 

by age, sex, race, Hispanic origin, and nativity, 

as of January 1, 1999.5 While we refer to this 

population as the base population for the series, 

the population universe for the series is defined 

by the estimates base population of April 1, 

1990. The estimates base population is the 

population that forms the base for national-level 

estimates produced for the Census Bureau’s 

population estimates program. This program 

yields the projections base population of January 

1, 1999. We refer to the population series from 

April 1, 1990, to January 1, 1999, as the base 

series for the projections. This series, and its 

associated estimates of the demographic 

components of change, form the data base from 

which most of the assumptions regarding 

fertility, mortality, and migration in the 

projections are formulated. 

The base population universe is derived primarily 

from the 1990 census and consists of residents of 

the 50 states and the District of Columbia. The 

universe excludes the U.S. Armed Forces 

overseas and citizens ordinarily residing outside 

the United States. It is subject to net 

underenumeration in the 1990 census, with the 

5 U.S. Census Bureau, “Population Growth Rate 

Remains Stable, Census Bureau Reports,” National Population 

Estimates, Released as Press Release No. CB99-101, June 4, 1999. 

At the time of release for this report, the results of the national 

estimates are located on the Census Bureau site of the Worldwide 

Web. U.S. Census Bureau; “National Population Estimates;” 

published June 1999, <http://www.census.gov/population/www 

/estimates/uspop.html> 

exceptions of adjustments for net 

underenumeration in certain localities resulting 

from the Census Test of 1995. The race 

distribution is modified to comply with the Office 

of Management and Budget Directive 15, which 

places all individuals within one of four major 

racial groups, 1) White, 2) Black, 3) American 

Indian, Eskimo, and Aleut, and 4) Asian and 

Pacific Islander.6 The age distribution is 

modified to eliminate the effect of inconsistencies 

between age and year of birth in the census, 

arising primarily from delayed reporting of an 

age inconsistent with the decennial enumeration 

date (April 1, 1990).7 

The Cohort-Component Method 

The cohort-component method for estimating 

and projecting a population, as previously 

indicated, is distinguished by its ability to 

preserve knowledge of an age distribution of a 

population (which may be of a single sex, race, 

and Hispanic origin) over time. It is a special 

case of a component method, which is defined 

simply by the use of estimates or projections of 

births, deaths, and net migration to update a 

population.8 In its simplest statement, the 

component method is expressed by the following 

equation: 

Pt = Pt-1 + Bt-1,t - Dt-1,t + Mt-1,t (1) 

where 

Pt

 = population at time t; 

Pt-1 = population at time t-1; 

Bt-1,t = births, in the interval from time t-1 to time t; 

Dt-1,t = deaths, in the interval from time t-1 to time t; and 

Mt-1,t = net migration, in the interval from time t-1 to time t. 

6 Throughout the remainder of this report, “American 

Indian” is used to describe the American Indian, Eskimo, and Aleut 

population. 

7 U.S. Census Bureau, Age, Sex, Race, and Hispanic 

Origin Information from the 1990 Census: A Comparison of 

Census Results with Results Where Age and Race Have Been 

Modified, CPH-L-74, U.S. Government Printing Office, Washington, 

District of Columbia, 1991. 

8 These methods are discussed in various demographic 

texts, e.g., Henry Shryock and Jacob Siegel, Methods and Materials 

of Demography, Academic Press, Orlando, Florida, 1976. 

U.S. Census Bureau January 2000 
U.S. National Projections 6 

Components of population change are estimated 

or projected separately, and applied to equation 

(1) recursively to produce a series of populations. 

We have not specified the measurement unit of 

time, so the interval from t-1 to t may be of any 

duration. 

The cohort-component method is based on 

similar logic for individual age groups, 

recognizing that the source population for a given 

age group is the population at time t-1 in the 

adjacent younger age group. For the initial age 

group, it is births during the interval from t-1 to 

t. For the moment, let us assume that the time 

unit is one year. The equation is replaced by two 

equations, depending on whether the age group is 

zero (meaning under 1) or any other age as of the 

last birthday, denoted by a. 

Pt(0) = Bt-1,t - Dt-1,t(0) + Mt-1,t(0) (2) 

Pt

(a) = Pt-1(a-1) - Dt-1,t(a) + Mt-1,t(a) (3) 

In the case of deaths (D) and net migration (M), 

the interval a denotes age of decedents or 

migrants at time t--not necessarily equal to age at 

time of death or migration. Each of the terms in 

equations (2) or (3), whether defined as a 

population or a number of events, relates to 

people born in a particular year (from t-a-1 to ta). Such a group is known as a birth cohort, 

hence the term “cohort component method.” 

While it is essential that age and time in 

equations (2) and (3) be measured in the same 

unit, there is no requirement that the interval be 

one year. For most applications, the time unit 

employed is either a single year or a five-year 

interval. 

The current projections are somewhat unusual in 

this regard, in that the time interval used is a 

calendar quarter. There are various reasons for 

the choice of quarter-year intervals. The base 

date for the series is April 1, 1990, while the 

reference date most frequently cited tends to be 

mid-year, or July 1. Data sources used to 

estimate the components of population change for 

the base series are produced for varying time 

intervals. Births and deaths are produced by 

calendar year; immigration data by federal fiscal 

year (ending September 30). Although these 

event data are based on administrative records 

coded by month, there would be no cost 

advantage in standardizing them to any particular 

year on the calendar. We therefore use the 

calendar quarter because it is the largest common 

subinterval of the various reporting intervals in 

the data. Extending the series to future dates by 

quarter facilitates the integration of future 

assumptions with base series data, and yields an 

added bonus of flexibility, in allowing users to 

either utilize the quarterly series or select any 

quarterly date for an annual series. 

The Inflation-Deflation Method 

The cohort-component method described above 

requires that the base population age distribution 

observe the fundamental attribute that birth 

cohorts are affected only by mortality and 

migration as they age. The population universe 

specified by the estimates base population does 

not observe this simple requirement for two 

salient reasons. First, the universe reflects 

underenumeration of the population at certain 

ages. Second, the misstatement of year of birth 

in the census causes spurious irregularities in the 

age distribution, especially “heaping” on certain 

terminal digits. If we did not employ the 

inflation-deflation method, the application of the 

cohort-component method would have the effect 

of advancing the age pattern of these 

irregularities over time, rendering age groups 

uncomparable from one year to the next. 

The inflation-deflation method is a procedure 

designed to overcome this problem. It can be 

summarized in six steps, each of which is carried 

out for each sex, race, Hispanic origin, and 

nativity category. 

1) An alternative base population universe, that 

is deemed to eliminate, or at least minimize the 

described irregularities in the age distribution, is 

utilized as a base population for cohort 

U.S. Census Bureau January 2000 
 

U.S. National Projections 7 

component projections. The population used 

here, known as a Demographic Analysis 

Population (DA population), is developed from 

an amalgam of historical data on births, deaths, 

and migration for ages under 65, and a 

population of Medicare enrollees for ages 65 and 

over. The reference date for this population is 

April 1, 1990.9 

2) An “inflation-deflation factor” is computed for 

each single-year age group, as the ratio of the 

estimates base population to the DA population 

in that group, both as of April 1, 1990. The 

resulting factors may be less than or greater than 

one, although they are more likely to be less than 

one, because the net effect of census 

underenumeration, census duplication, age 

heaping, and discrepancies in racial classification 

are more likely to be negative than positive. 

3) The DA population by age is updated from 

April 1, 1990 to January 1, 1999, then projected 

to future dates, by the cohort-component method, 

per equations (2) and (3), as described earlier. 

Births, deaths, and foreign-born emigrants by age 

are derived by application of rates, to be 

discussed in the next section. 

4) The population in each age group is multiplied 

by the inflation-deflation factor for the group, for 

each quarterly reference date. While the factors 

are defined for full-year age groups, they are 

assumed to be constant across quarter-year ages 

within the full-year groups. 

5) The actual base population for the projections, 

the estimates base universe, is projected using the 

simple component method without distribution by 

age, per equation (1) described earlier. The total 

number of births, deaths, and foreign-born 

emigrants from January 1, 1999, forward are 

those derived in step 3), with results summed 

9 For a description of the 1990 Demographic Analysis 

population and its derivation, see J. G. Robinson, B. Ahmed, P. Das 

Gupta, and K.A. Woodrow, “Estimation of Population Coverage in 

the 1990 United States Census Based on Demographic Analysis,” 

Journal of the American Statistical Association, Vol. 88-423 

(1993): pp. 1061-1071. 

across age groups. Because the number of births 

is considered to be adjusted for underregistration, 

births are reduced by a factor to reflect what 

would actually be registered. The balance of the 

migration components are derived numerically 

via the projection assumptions, to be discussed 

later in this report. 

6) A pro-rata adjustment is used to force the age 

distributions from step 4) to match the population 

totals from step 5). 

Derivation of Births, Deaths, and ForeignBorn Emigration from Rates 

The application of the cohort-component method, 

as stated in equations (2) and (3) requires 

numerical projections of births, deaths, and net 

migration. The formulation of assumptions (see 

below) yields numerical projections of the net 

migration component (without the effect of 

foreign-born emigration) for the full matrix of 

characteristics for each quarter. These numerical 

projections are exogenous, in the sense that they 

are unaffected by population. However, the 

assumptions yield population-based rates of 

fertility, mortality and foreign-born emigration. 

Therefore, the resulting numerical projections of 

these components are endogenous, meaning they 

are themselves partly a consequence of the 

projected population. The derivation of 

numerical projections of endogenous components 

is part of step 3) in the procedure described in the 

previous section. Because the projection 

procedure produces the population at quarterly 

intervals, the application of rates occurs for each 

quarterly interval and by quarter year of age. 

Mortality and emigration rates are applied to the 

mid-quarter population of each age group as the 

population is generated, taking account of the 

fact that mortality and migration, along with the 

exogenous components, affect the mid-quarter 

population in its generation. Equation (3) is 

applied to produce all quarter-year age groups 

for the beginning of the succeeding quarterly time 

interval. Fertility rates are then applied to midquarter populations of female age groups to 

U.S. Census Bureau January 2000 
U.S. National Projections 8 

generate births, and mortality and emigration 

rates for first-quarter infants are applied to 

complete the youngest age group, per equation 

(2). 

An exception to this procedure occurs in the case 

of the foreign-born population. Foreign-born and 

native women of the same age, race, and 

Hispanic origin are assumed to have the same 

fertility and mortality rates, since the base data to 

differentiate fertility and mortality by nativity 

were unavailable. It was therefore convenient to 

project the population of both nativity categories 

together, then project the foreign-born population 

by assuming zero fertility, since all newly born 

are native by definition. The native population 

could then be determined by subtracting foreignborn from total population. 

The projection assumptions produce rates for full 

years of age, and full-year rates are assumed 

constant across quarter-year subdivisions of age. 

However, empirical observation of the 

seasonality of death and childbearing is 

considered in the derivation of deaths and births 

by quarter. Data from the National Center for 

Health Statistics for calendar year 1996 provide 

the basis for the seasonal distribution of annual 

births and deaths.10 Foreign-born emigration 

rates are projected from information for an entire 

decade, so no information on seasonality was 

available, and none was assumed. For foreignborn emigration the quarterly series was 

determined by the quarterly application of 

emigration rates to the foreign-born population. 

Reflecting Uncertainty of Assumptions 

Through High and Low Variants 

The new projections do not include a systematic 

measurement of uncertainty. However, in the 

10 For seasonality of births see Stephanie J. Ventura, J. 

Martin, S. Curtin, T. Mathews, National Center for Health Statistics, 

Report of Final Natality Statistics, 1996, Monthly Vital Statistics 

Report, Vol. 46-11 Supplement, 1998.; for seasonality of deaths see 

unpublished tabulations from National Center for Health Statistics, 

1996 detailed mortality file. 

development of each of the component 

assumptions, we established high and low 

variants based on a reasoned assessment of what 

represented “extreme” values. Applying variant 

assumptions for each component individually 

resulted in the range of population series that 

would be identified with the maximum likely 

variance of that component. To produce our 

lowest and highest series, we combined the 

extreme values of all three major components 

that favored, respectively, the lowest and highest 

population growth. Therefore, the extreme 

projections do not represent likely scenarios in 

themselves, but purport to represent the extremes 

between which most likely outcomes should fall. 

Fertility and international migration imposed a 

greater uncertainty on the projections than did 

mortality, because childbearing and mobility, to a 

greater extent than death, are functions of 

individual and collective decision-making that are 

difficult to forecast accurately. 

ASSUMPTIONS FOR THE COMPONENTS 

OF CHANGE 

The following sections describe the assumptions 

that determined future levels of fertility, 

mortality, and international migration, for 

application of the methodology described above. 

Fertility 

The total fertility rate (TFR) for the United 

States has remained fairly constant since 1989.11 

As of 1997, the total fertility rate was 2,032.5 

births per 1,000 women.12 Evaluating the 

fertility trends of the recent past is useful in 

establishing the immediate direction of fertility. 

11 The total fertility rate is a standardized measure of the 

average number of live births per 1,000 women experiencing specific 

age-specific fertility rates throughout their childbearing years without 

accounting for mortality. 

12 Stephanie J. Ventura, J. Martin, S. Curtin, T. Mathews, 

National Center for Health Statistics, Births: Final Data for 1997, 

National Vital Statistics Report, Vol. 47-18, 1999. 

U.S. Census Bureau January 2000 
 

 

 

U.S. National Projections 9 

However, such evaluation provides little 

information regarding the trend for the next 100 

years. To formulate our fertility assumptions, we 

relied on demographic theory, analyzed past and 

current national and international fertility trends, 

and made use of data on birth expectations from 

a national survey. 

Assumptions and Methodology 

The previous projections assumed constant 

fertility throughout the projection period by race 

and Hispanic origin for the middle series.13 The 

fertility assumptions for the current set of 

projections allow fertility to vary for the shortand long-term by race and Hispanic origin. 

Fertility trends are projected separately for nonHispanic Whites, non-Hispanic Blacks, nonHispanic American Indians, non-Hispanic Asian 

and Pacific Islanders, and Hispanics.14 

Short-term Fertility Assumptions 

To project the short-term fertility trends, the 

period from 1999 to 2025, we assumed fertility 

levels will reach target total fertility rates 

determined by birth expectations data and 

demographic theory. Once collected and 

analyzed, birth expectations are used to represent 

the total number of children ever born for three of 

the five race and Hispanic origin groups in 2025. 

The birth expectations are 

further adjusted according to the method 

developed by van Hoorn and Keilman.15 Because 

birth expectations data for non-Hispanic 

American Indians and non-Hispanic Asian and 

Pacific Islanders are deficient, total fertility rates 

are derived for these groups by assuming they 

converge halfway to “replacement level,” a total 

fertility rate of 2,100 per 1,000 women, by the 

13 Jennifer Cheeseman Day, U.S. Census Bureau, 

Population Projections of the United States by Age, Sex, Race, and 

Hispanic Origin: 1995 to 2050, Current Population Reports, P25­

1130, U.S. Government Printing Office, Washington, District of 

Columbia, 1996. 

14 Each sub-group of Hispanics is assumed to maintain 

identical fertility trends. 

15 W. van Hoorn and N. Keilman, “Birth Expectations 

and Their Use in Fertility Forecasting,” Eurostat Working Papers, 

E4/1997-4 (1997). 

year 2025. The total fertility rate for nonHispanic American Indians and non-Hispanic 

Asian and Pacific Islanders is assumed to decline 

by .006 and .002 births per woman per year 

respectively between 1998 and 2025. 

Long-term Fertility Assumptions 

Beyond the year 2025, we relied upon an analysis 

of past and current national and international 

fertility trends and demographic theory to 

formulate our assumptions. However, a review 

of fertility trends and existing research by 

Westoff16 and Day,17 among others, provide no 

definitive long-term direction for the fertility of 

the United States. Therefore, following 2025, 

long-term total fertility rates for each race and 

Hispanic origin category are assumed to move 

regularly toward replacement level, reaching 2.1 

in 2150. The rate of increase or decrease to the 

total fertility rates differ among the five race and 

Hispanic origin groups. Table B displays the 

total fertility rates by race and Hispanic origin 

for the projections period of 1999 to 2100. 

Long-term Assumptions for Fertility by Race 

and Hispanic Origin 

Because the long-term assumptions project a 

slow stabilization of the total fertility rate, in 

about 150 years, the fertility rates of racial and 

Hispanic origin groups are posited to slowly 

converge. Historically, such convergence was 

not exhibited by non-Hispanic Blacks, 

particularly in reference to non-Hispanic Whites. 

While non-Hispanic Whites maintained total 

fertility rates near 2.0 and 2.1 between 1989 and 

1993, non-Hispanic Blacks experienced rates 

between 2.4 and 2.6.18 However, since 1993 

16 Charles Westoff, “The Return to Replacement Level 

Fertility: A Magnet Force?” Future of Demographic Trends in 

Europe and North America, Academic Press, London, England, 

1991. 

17 Lincoln H. Day, “Recent Fertility Trends in 

Industrialized Countries: Toward a Fluctuating or Stable Pattern?” 

European Journal of Population, Vol. 11 (1995): pp. 275-288. 

18 Stephanie J. Ventura, J. Martin, S. Curtin, T. 

Mathews, National Center for Health Statistics, Report of Final 

Natality Statistics, 1996, Monthly Vital Statistics Report, Vol. 46-11 

Supplement, 1998. 

U.S. Census Bureau January 2000 
 

 

U.S. National Projections 10 

non-Hispanic Black fertility has declined and 

converged toward non-Hispanic White fertility 

rates. 

Fertility trends for particular Hispanic and Asian 

and Pacific Islander groups also diverge from 

national trends. These groups, however, are 

comprised predominately of foreign-born 

populations which generally maintain higher 

fertility rates than native women of the same race 

and origin group.19 According to assimilation 

theory, the longer an immigrant female remains 

in the U.S., the more likely she will be to adopt 

fertility behaviors of native women of the same 

racial or Hispanic origin group. Researchers 

have found evidence to support the assimilation 

theory in regard to foreign-born and native 

fertility trends within the United States.20 

Therefore, fertility rates among Hispanic and 

Asian and Pacific Islander women are assumed to 

converge with national levels. In addition, 

exogamy and interracial childbearing are 

projected to increase in the future, further 

diminishing fertility differentials among racial 

and Hispanic origin groups. 

Methodology 

The middle series age-specific fertility rates were 

calculated for women 10 to 49 years old by 

single year of age and five race and Hispanic 

origin groups from 1999 to 2100. To begin, 

single year age-specific fertility rates were 

calculated using birth registration data from the 

National Center for Health Statistics and 

population estimates for 1996 to 1998. Agespecific fertility rates by race and Hispanic origin 

for 1996 and birth registration data by race and 

Hispanic origin (adjusted for under-registration) 

19 Martin O’Connell, U.S. Census Bureau, Studies In 

American Fertility, Current Population Reports, P23-176, U.S. 

Government Printing Office, Washington, District of Columbia, 

1991. 

20 Joan R. Kahn, “Immigrant and Native Fertility During 

the 1980s: Adaptation and Expectations for the Future,” 

International Migration Review, Vol. 28-3, (1994): pp. 501-519.; 

and Deanna Pagnini, “Immigration and Fertility in New Jersey: A 

Comparison of Native and Foreign-Born Women,” pp. 259-290 in 

Keys to Successful Immigration, Urban Institute Press, Washington, 

District of Columbia, 1997. 

for 1997 and 1998 were available. However, at 

the time of production, birth registration data by 

age of the mother were not available for 1997 

and 1998. Therefore, total births by mother’s 

age and race were calculated for 1996, 1997 and 

1998 using indirect standardization. The base 

population used to create the age-specific fertility 

rates was the mid-year population of the 

Demographic Analysis (DA) universe, as defined 

for purposes of the inflation-deflation method, 

described above.21 

The 1995 National Survey of Family Growth 

Cycle V (NSFG Cycle V) data set were obtained 

and birth expectation data were calculated for 

women 15 to 44 years of age.22 Total fertility 

rates were adjusted by reducing birth 

expectations for non-Hispanic Whites and nonHispanic Blacks as proposed by the van Hoorn 

and Keilman method and supported by findings 

from the National Center for Health Statistics.23 

The model developed by van Hoorn and Keilman 

adjusts birth expectations to account for issues of 

uncertainty, period fertility, and “limiting 

factors.” Because the NSFG Cycle V adjusts for 

item non-response and total non-response, and 

the period adjustment is unnecessary as specified 

by the proposed method, the birth expectations 

were only reduced by 10 percent to account for 

the “limiting factors,” which generally result in 

overestimation. 

Once births by single year of age of the mother 

were calculated, a single set of age-specific 

fertility rates were calculated and imputed to 

1998 for purposes of the projections. Because 

21 Age-specific fertility rates calculated for the 

projections differ from those calculated by the National Center for 

Health Statistics as a result of applying different base populations. 

22 National Center for Health Statistics, National Survey 

of Family Growth, Cycle V, 1995. 

23 According to the National Center for Health 

Statistics, “The expectations of young women 25-29 years of age in 

1988 exceed the estimated completed fertility of women in their 

earliest 40’s at the time by about 9 percent (the difference between 

2.33 and the average of 2.07, 2.12, and 2.17, above).” In Linda S. 

Peterson, National Center for Health Statistics, Birth Expectations 

of Women in the United States, 1973-88, Vital and Health Statistics, 

Vol. 23-17, 1995: p. 8. 

U.S. Census Bureau January 2000 
U.S. National Projections 11 

separate short- and long-term assumptions were 

made, rates for each of the five race and Hispanic 

origin groups were interpolated separately from 

1998 to 2025 and 2025 to 2100 to reach target 

total fertility rates. Age-specific fertility rates for 

Whites, Blacks, American Indians, and Asian 

and Pacific Islanders, with the Hispanic and nonHispanic component of each group combined, 

were calculated after completing the projections. 

Low and High Fertility Assumptions 

The fertility assumptions for the highest and 

lowest series are based on a proportional increase 

or decrease relative to the middle series. The 

range widens steadily as an acknowledgment of 

increased uncertainty, although the series do not 

represent statistical confidence intervals. The 

assumptions required the calculation of an 

increase and decrease to the middle series agespecific fertility rates by a series of proportions. 

The proportions were interpolated linearly from 

zero in 1998 to reach 15 percent in 2025, and 

from there to 25 percent in 2100. Inflating the 

middle series fertility rates by this series of 

proportions yields the high variant, while 

deflating it by the same proportion yields the low 

variant. The total fertility rates by race and 

Hispanic origin for the middle, low, and high 

series for the projections period of 1999 to 2100 

are detailed in Table B. 

Mortality 

At the present time, significant mortality 

differentials exist between males and females and 

between race and ethnic groups in the U.S. Life 

expectancy at birth (hereafter abbreviated as “life 

expectancy”) has generally increased throughout 

the century for both sexes and for Whites and 

Blacks. For other race and ethnic groups, 

however, data are too scarce to identify trends 

over time. Throughout the 20th century, 

differentials in life expectancy between males and 

females, and between Blacks and Whites, have 

been quite irregular, increasing in some periods, 

and decreasing in others. During the 1990's, the 

differentials between males and females, and 

between Blacks and Whites, have tended to 

narrow. By 1997, life expectancies for males 

and females had reached 73.6 and 79.4 

respectively.24 

In order to project age-specific death rates 

(ASDRs) and life expectancies, we construct 

current ASDRs by sex, race, and Hispanic origin 

groups for use as a projection base, using deaths 

provided by the National Center for Health 

Statistics (NCHS) and our own population 

denominators. Readers with an interest in the 

full details of these procedures are referred to the 

latter part of this section. As discussed later, 

data are not available to allow accurate 

measurement of ASDRs and life expectancies for 

all race and Hispanic origin groups. 

Table C shows fairly large differences in life 

expectancy between males and females, and 

across race and Hispanic origin groups for the 

first projected year (which is very similar to the 

1998 base period).25 Our projections assume a 

narrowing of the observed mortality gaps among 

race and Hispanic origin groups over time, such 

that by year 2100 the ASDRs of the race and 

Hispanic origin groups are much closer together 

than what is observed today. We also assume a 

slight narrowing of the sex gap in mortality over 

the next 100 years. As discussed in detail in the 

next section on assumptions and methodology, 

our projection models are based on a mixture of 

projected data by other researchers, with our own 

research incorporated into the models. For 

example, we use the research of Lee and 

Tuljapurkar as a source of overall life 

24 For detailed information on mortality trends between 

1900 and 1990, see Robert N. Anderson, National Center for Health 

Statistics, U.S. Decennial Life Tables for 1989-91, Vol. 1-3, 

Hyattsville, Maryland, 1999. 

For mortality patterns trough 1997 and mortality rates for 

the five race and Hispanic origin groups see Donna L. Hoyert, K. D. 

Kochanek, and S. L. Murphy, National Center for Health Statistics, 

Deaths: Final data for 1997, National Vital Statistics Reports, Vol. 

47-19, Hyattsville, Maryland, 1999. 

25 In this mortality section, the term "race and Hispanic 

origin groups" refers specifically to five groups: Hispanic, NonHispanic White, Non-Hispanic Black, Non-Hispanic American 

Indian, and Non-Hispanic API. We use “race and ethnicity” in a 

more general sense to include all race and ethnic groups. 

U.S. Census Bureau January 2000 
 

 

 

U.S. National Projections 12 

expectancy levels for males and females 

separately (without regard to race and Hispanic 

origin) for year 2065, but we use our own 

extrapolations for dates beyond that.26 Thus, Lee 

and Tuljapurkar’s research influences our 

assumption about the future sex differential, but 

our assumptions about future race and Hispanic 

origin differentials are generated internally. A 

few methodological considerations led to our 

assumption of declining race and Hispanic origin 

mortality differentials. First, such differentials, 

even for the current period, are difficult to 

estimate accurately. The definitions of race and 

origin are themselves mutable and ever-changing. 

Second, and related to the above, increasing rates 

of intermarriage may serve to reduce differentials 

in the future. 

Assumptions and Methodology 

The previous projections report projected 

survival rates primarily by extrapolating past 

annual rates of change, separately by age, sex, 

race and Hispanic origin group.27 In the current 

set of projections we create male and female 

target life tables corresponding to a far-future 

year (2150, which is beyond our projection 

horizon), and we force the base life tables (which 

are discussed later) for the separate race and 

Hispanic origin groups to converge over time to 

these target life tables.28 The end result of this 

process is a slight narrowing of the sex difference 

in mortality over time, and a more prominent 

narrowing of race and Hispanic origin differences 

over time, such that by year 2100 the race and 

origin groups are quite a bit more similar in their 

life expectancy than they are today. The year 

26 Ron Lee and S. Tuljapurkar, Population Forecasting 

for Fiscal Planning: Issues and Innovations, unpublished 

manuscript, September, 1998. 

27 Jennifer Cheeseman Day, U.S. Census Bureau, 

Population Projections of the United States by Age, Sex, Race, and 

Hispanic Origin: 1995 to 2050, Current Population Reports, P25­

1130, U.S. Government Printing Office, Washington, District of 

Columbia, 1996. 

28 We use the term “life table” throughout this text for 

convenience. Most of our work is actually based on schedules of 

age-specific central death rates, which can be converted to life tables 

and used to calculate life expectancies at birth and at age 65. 

2150 was chosen as a target for race and ethnic 

convergence because it allowed our models to 

yield plausible rates of mortality decline over 

time for each sex, race, and Hispanic origin 

group. 

A few different sources of information entered 

into the construction of the year 2150 target life 

tables for males and females. First, we used 

projected life expectancies for total males and 

females (all race and Hispanic origin groups 

combined) for the year 2065 produced by Lee 

and Tuljapurkar,29 which updates the original 

Lee-Carter stochastic time-series model.30 For 

our middle series, these year 2065 life 

expectancies are 83 for males and 88 for 

females.31 Second, we used expert opinion 

regarding how much faster the mortality rates of 

some age groups will decline in the future relative 

to the others. These were obtained by utilizing 

the results of a survey conducted at the 1997 

mortality projection conference sponsored by the 

Society of Actuaries.32 We use the term 

“decline” to mean annual average rate of 

mortality decline in the rest of this section. 

Survey results are shown below. 

Age 0-14 vs. 65+ Age 15-64 vs. 65+ 

“Next 10 years” 2.1 1.3 

“After 25 years” 1.6 1.2 

For example, most participants at the Society of 

Actuaries conference predict that the decline 

experienced by the age group under 14 years will 

be 2.1 times that of the age group 65 years and 

29 Ron Lee and S. Tuljapurkar, Population Forecasting 

for Fiscal Planning: Issues and Innovations, unpublished 

manuscript, September, 1998. 

30 Ron Lee and L. Carter, “Modeling and Forecasting US 

Mortality," Journal of the American Statistical Association, Vol. 

87-419 (1992): pp. 659-675. 

31 Personal correspondence, Carl Boe for Lee and 

Tuljapurkar 10/19/98. 

32 Margorie Rosenberg and Warren Luckner, “Summary 

of Results of Survey of Seminar Attendees,” North American 

Actuarial Journal, Vol. 2-4 (1998): pp. 64-82. 

U.S. Census Bureau January 2000 
U.S. National Projections 13 

older over the “next ten years.” 

Instead of “next 10 years” and “after 25,” as 

reported in the Society of Actuaries report, we 

used two time periods: 1990 to 2020 and 2021 to 

2150. This was done because one of our 

projection base years is 1990 (as discussed later), 

and we wanted to adapt the Society of Actuaries 

report data to fit our data requirements. We also 

constrained the age group 65 years and older 

decline to be the same for the two time periods, 

since there is no information in the Society of 

Actuaries report about the 65 years and older 

decline for time periods before year 2020. 

With the above-mentioned projected life 

expectancies and ratios, and with a base set of 

ASDRs by sex, race, and Hispanic origin, we 

obtain declines out to the year 2150 that satisfy 

the above conditions (four ratios representing age 

patterns of decline over time) as well as the 

conditions involving life expectancies for year 

2065 as explained above. Given the assumed 

fixed relationships between the declines across 

the broad age groups over time, there is only one 

trend that needs to be derived, which is the 

decline for the age group 65 years and older. We 

then use these declines to produce ASDRs and 

life tables for males and females in 2150. This is 

done by a simple extrapolation which assumes 

that the declines that led to year 2065 life tables 

will continue thereafter. Projected ASDRs for 

each sex, race, and Hispanic origin group are 

then derived by interpolating between the 1990 

base ASDRs (by each sex, race, and Hispanic 

origin) and the year 2150 ASDRs, a procedure 

which reflects our race and Hispanic origin 

convergence assumption. This yields life tables 

for the ten groups which are consistent with the 

year 2065 male and female life expectancies (all 

race and origin groups combined) projected by 

Lee and Tuljapurkar. 

However, we do not present life expectancies and 

ASDRs for years beyond 2100--those data points 

are beyond our projection horizon, and were 

developed solely to achieve a narrowing of 

differentials over time within the projection 

period (to 2100). Year 2150 was chosen because 

it yields the most acceptable rates of mortality 

decline for the sex, race, and ethnic groups. For 

example, using year 2100 as a target life table 

would yield too rapid rates of mortality decline 

for some subgroups, in our opinion. 

Table C shows projected life expectancies for 

each of the ten specific sex, race, and Hispanic 

origin groups. Life expectancies for aggregations 

of these groups (White, Black, American Indian, 

and API) are based on life tables we constructed 

at a later stage using weighted averages of 

ASDRs. To weight the averages, we used the 

separate sex and race populations (in the case of 

race aggregation) or the separate sex populations 

(in the case of sex aggregation) (not shown). 

Low and High Mortality Assumptions 

As discussed earlier, the year 2150 target life 

tables for males and females are based partly on 

Lee and Tuljapurkar's projected life expectancies 

for year 2065 (83 for males, 88 for females). The 

low and high life expectancy series are 

constructed using the same methodology and data 

as the middle series, except that different values 

are used for year 2065 life expectancies. For the 

low life expectancy series, we use 81 and 86 for 

males and females respectively. For the high life 

expectancy series, we use 86 and 90 for males 

and females respectively. These low and high 

values are the lower limit and upper limit 

respectively of the 95 percent confidence interval 

reported by Lee and Tuljapurkar.33 Thus, we end 

up with a set of male and female target life tables 

(year 2150) for each of the three series. The 

procedures for producing the ASDRs for all 

intervening years between the base and target 

(year 2150) years, and for the sex, race, and 

ethnic groups, are identical across the three 

series. As expected, there is an increasing 

divergence of life expectancies over the course of 

the projection period between the low and high 

series, for any given sex, race, and ethnic group. 

33 Personal correspondence, Carl Boe for Lee and 

Tuljapurkar 10/19/98. 

U.S. Census Bureau January 2000 
U.S. National Projections 14 

Two Sets of Base Mortality Rates: General 

Issues 

While the general procedure to obtain projected 

ASDRs for all sex, race, and Hispanic groups 

involves interpolation between a base set of 

ASDRs (one set for each sex, race, and Hispanic 

origin subgroup) and year 2150 target ASDRs 

(one set for each sex, as described earlier), the 

procedures are, in fact, more complicated 

because we use two sets of base ASDRs at 

different stages of the projection process. 

We first create the long-term series of ASDRs 

out to year 2150 using 1990 ASDRs as a starting 

point. We call these 1990 ASDRs the "primary 

base.” We construct these base ASDRs using 

1990 deaths from NCHS and 1990 census 

population denominators, by sex, race, and 

Hispanic origin. We consider these to be more 

appropriate for projecting a long-term series, as 

compared with rates which use our postcensal 

population estimates as denominators. Yet, we 

prefer to have a smooth transition from our 

national estimates in 1998 to our national 

projections for subsequent years. In order to 

avoid sharp breaks between the ASDRs for 1998 

(and earlier) assumed in our national estimates, 

and those assumed for the projections for 1999 

and beyond, we subsequently create a new set of 

ASDRs for 1999 through 2020 for use in the 

projections. These new ASDRs are produced by 

interpolating from the 1996 to 1998 combined 

ASDRs of the national estimates series (which 

we refer to here as the "secondary base") to the 

year 2021 ASDRs of the projection series that 

was based on the primary base, for each sex, 

race, and Hispanic origin group. We call these 

new and more consistent ASDRs the "bridge 

series,” and we replace the original 1999 to 2020 

projected ASDRs with this bridge series, in order 

to smooth out the transition from national 

estimates to national projections. 

Base Mortality Rates: Detailed Construction 

Procedures for constructing the primary base 

ASDRs are discussed below. Because the 

procedures for constructing the secondary base 

ASDRs are similar, we do not repeat those here. 

Base ASDRs are constructed with 1990 deaths 

obtained from NCHS (by age, race, and Hispanic 

origin) divided by a July 1, 1990, population in 

the demographic analysis (DA) universe (as 

discussed under “inflation-deflation”) for the 

appropriate subgroup. All ASDRs in this study 

are central death rates, and based on single years 

of age. Although we obtain NCHS deaths for 

Whites, Blacks, American Indian, API, and 

Hispanics, we do not obtain deaths for the nonHispanic portions of the four racial groups. The 

latter are constructed using a series of steps 

described below. 

Mortality Rates by Hispanic Origin 

We first calculate Hispanic ASDRs using a 45­

state 1990 numerator of Hispanic deaths and a 

corresponding 45-state Hispanic population 

denominator (1990 uncorrected, census-level). 

We excluded five states either because they did 

not collect Hispanic origin on the death 

certificate (Louisiana, New Hampshire, and 

Oklahoma) or because they had relatively high 

proportions of unknown Hispanic origin 

(Connecticut and New York). Excluding these 

five states eliminates most of the approximately 

106,000 unknown Hispanic origin deaths (5 

percent of all deaths) that appear in the 1990 

NCHS mortality files. Among the 45 states, only 

0.67 percent of the deaths are of unknown 

Hispanic origin and are excluded from the 

calculation of ASDRs (probably contributing to 

an underestimation of Hispanic death rates). 

The following steps are used to derive ASDRs 

for the non-Hispanic portions of racial groups: 

1) We obtain estimated numbers of deaths to 

Hispanic White, Hispanic Black, Hispanic 

American Indian, and Hispanic API by 

multiplying the Hispanic ASDRs by the 

Hispanic portion of each race population (DAlevel), by age and sex. 

2) We obtain estimated numbers of deaths to four 

race (any Hispanic) groups by multiplying race 

(any Hispanic) ASDRs by the respective race 

populations. 

U.S. Census Bureau January 2000 
U.S. National Projections 15 

3) Subtracting 1) from 2) yields deaths to NonHispanic White, Non-Hispanic Black, NonHispanic American Indian, and Non-Hispanic 

API, by age and sex. 

4) ASDRs for each sex, race, and Hispanic 

origin group are then obtained by dividing these 

deaths by their respective sex, race, and Hispanic 

origin population denominator. 

Problems With Race and Hispanic Origin 

Mortality Rates 

There are well-known difficulties in calculating 

accurate mortality rates for some race and 

Hispanic origin groups in current or past years, 

including both the 1990 primary base years and 

the 1996 to 1998 secondary base years. The 

numerators and denominators of the ASDRs 

come from different sources, and they differ in 

important ways. Some of these differences 

include 1) how race and ethnicity is reported and 

classified (being self-reported in the census, but 

not self-reported on death certificates) 2) how 

missing data are handled, and 3) how responses 

such as “other race” are handled. Thus, there is 

inconsistent reporting of race and ethnicity 

between the two data sources--death records and 

census records. There is convincing evidence 

that the ASDRs for some race and ethnic groups, 

as currently measured, are underestimated. One 

study that compared race and ethnic 

identification on CPS surveys with those of death 

certificates suggests that API death rates could 

be underestimated by 12 percent, and by 25 

percent for American Indians.34 35 However, we 

34 P. Sorlie, E. Rogot, and N. Johnson, “Validity of 

Demographic Characteristics on the Death Certificate,” 

Epidemiology, Vol. 3-2 (1992): pp. 181-184. 

Additional discussion and evidence related to the 

underestimation of American Indian mortality can be found in U.S. 

Department of Health and Human Services, Indian Health Service, 

1997 Trends in Indian Health, Rockville, Maryland, 1997.; and in 

Support Services International, Inc., Adjusting for Miscoding of 

Indian Race on State Death Certificates, Final Report Submitted to 

the Division of Program Statistics, Indian Health Service, 1996. 

35 The use of the DA universe for population 

denominators tends to obviate biases of differential reporting between 

Blacks and all other races combined, since the DA procedure uses 

death registration data to define these categories. However, the break 

of “other race” into American Indian, API, and White required the 

use of census data, with all it’s biases relative to death registration. 

do not yet know of an adequate way to adjust our 

race and ethnic mortality rates, and correction 

factors are not available at this time. We 

currently use the existing data until we have a 

stronger basis for making adjustments. 

Old-age Mortality Rates 

We do not calculate ASDRs for the age group 85 

years and older in the same manner as we do for 

the under 85 years population (i.e, NCHS deaths 

divided by population denominators), due to the 

inaccuracies that can result from such a 

procedure. There are problems of age misreporting in both the numerators (death records) 

and denominators (census-based population 

data). Instead, we use a mathematical model 

developed by Coale and Kisker to obtain ASDRs 

for each subgroup.36 We inserted different 

parameters into the original Coale and Kisker 

formulas in order to force them to produce death 

rates of 1.0 for both males and females at age 

115 for all race and Hispanic origin groups. 

International Migration 

Among the three major components of national 

population change--births, deaths, and 

international migration--international migration is 

the component for which demographic science 

offers the least to future projections. Births and 

deaths can be projected as rates, with 

demographic detail, so the emerging size and 

structure (age, sex, race, and Hispanic origin) of 

the populations at risk of death and childbearing 

are a key determinant of these components of 

population change. Moreover, the 

epidemiological basis for the propensity to die, 

as well as the social and economic basis for the 

propensity to bear children are both the subjects 

of substantial academic inquiry. This body of 

research has yielded a basis for projecting their 

future course, as reflected in previous sections of 

36 Ansley Coale and E. Kisker, “Defects in Data on OldAge Mortality in the U.S.: New Procedures for Calculating Schedules 

and Life Tables at the Highest Ages,” Asian and Pacific Population 

Forum,Vol. 4-1 (1990): p. 32. 

U.S. Census Bureau January 2000 
U.S. National Projections 16 

this report. International migration to the United 

States, by contrast, has public policy as a major 

determinant. While it may be acceptable in the 

near term to view migration as a consequence of 

existing immigration law and policy, this 

assumption loses merit for the longer term. 

Emigration of the foreign-born population can be 

projected relative to a population at risk (e.g., the 

foreign-born population) through the use of 

emigration rates, but there is little or nothing in 

the way of theory to indicate how these rates 

might change over time. 

Assumptions and Methodology 

International migration, in previous United States 

population projections produced by the Census 

Bureau, has been projected as a constant value 

with a constant matrix of demographic 

characteristics. The constant-level assumption 

has been based on the experience of the last few 

years prior to the launch date of the projections, 

incorporating separate assumptions for legal 

immigration, refugee movements, emigration (of 

natives and foreign-born combined), net 

migration from Puerto Rico, and net 

undocumented migration. High and low variants 

have been determined by establishing reasonable 

maximum and minimum values of each of these 

components, and holding them constant over 

time, with a linear transition over a few years 

from current to ultimate values. 

The current projection series incorporate three 

major changes from past practice in the 

projection of international migration. First, we 

decided that the constant migration assumption 

was inappropriate for a projection series (the 

middle series) that would be widely interpreted as 

the Census Bureau’s forecast of population. 

This determination was primarily on account of 

an increased level of public debate regarding 

immigration policy, as well as the highly 

transitory nature of some recent developments in 

international migration. The former mandated a 

more critical view of how migration might 

change in the future, while the latter tended to 

discredit the interpretation of the base series in a 

simplistic manner. However, we have not been 

able to develop a dynamic model for future 

international migration that reflects adequately 

the current base series information, yet conforms 

to any unifying theory of future change. We 

have, therefore, projected migration with 

consideration of a large amount of underlying 

current detail, coupled with some consideration 

of factors that could influence its change in the 

future. The resulting projections seek to reflect 

current trends in specific aspects of migration, 

and to gauge their likely future direction and 

magnitude. 

The second change from past practice is that we 

allow characteristics of the projected population 

to influence the migration assumption. In the 

past, we have expressly avoided incorporating 

population “feedback” mechanisms when 

formulating assumptions on any components of 

population change, assuming a unidirectional 

causative sequence from determinants of 

components to components and from components 

to the population. In the case of fertility and 

mortality, we continue this practice, simply 

because there is little evidence that such 

feedbacks are important. In order to develop a 

dynamic assumption regarding future migration, 

it is necessary to consider the plausible links that 

tie demographic characteristics of the future 

population to immigration policy. Thus, we 

consider the future direction in the age 

composition of the population, as it might affect 

policy regarding the immigration of working-age 

people. 

A third major innovation in the current 

projections of international migration relates to 

the projection of the emigration of foreign-born 

residents. Because we have projected the 

foreign-born population in the current 

projections, we were able to model foreign-born 

emigration as a function of the population at risk, 

in much the same way as we projected mortality. 

Thus, foreign-born emigration is projected, in all 

series, as rates by age, and sex, rather than as 

number of emigrants. The comparatively low 

level of native-born emigration is projected 

numerically, as in the past. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 17 

We are unable to project total in-migration and 

total out-migration, as we have no such estimates 

in the base series. For some of the components 

of international migration, information sources 

for the base series offer no disaggregation of 

gross in-migration from gross out-migration. 

Specifically, the net flow of migrants from Puerto 

Rico (treated as international in this context), the 

net flow of undocumented migrants from foreign 

countries, and the net flow of other legal nonimmigrant residents (mostly foreign students) are 

imputed only as net flows--not as a balance of 

measured in- and out-migration. Consequently, 

the concept of “in-migration” to the U.S. in these 

projections is a somewhat artificial construct 

consisting of in-migration of refugees, inmigration of newly arriving legal immigrants, inmigration of non-immigrants who will later 

become legal immigrants, net undocumented 

migration, net Puerto Rican migration, and the 

net movement of other legal but temporary nonimmigrants to the United States. This flow is in 

large part a one-way flow to the U.S., but 

embodies some reverse elements in the 

components only measurable as net flows in the 

base series. By the same token, the separately 

projected “out-migration” component is confined 

to the emigration of legal permanent U.S. 

residents to permanent residence abroad, 

excluding resettlement in Puerto Rico. 

Table D provides a summary of “in-migration” 

(as previously described) and the emigration of 

legal residents for four single years in the 

projection series. 

Projection of the Level of In-Migration: 

Middle Series, 1999 to 2020 

The determination of the trend in migration to the 

United States from 1999 to 2020 in the middle 

series is based on consideration of current trends 

in the arrival of people born in different areas of 

the world. The trend is based on the following 

guiding assumptions. 

1) A rapid increase in the level of migration 

during the 1990's occurred largely because 

millions of people legalized in 1987 and 1988 

under the Immigration Reform and Control Act 

(IRCA) of 1986, were becoming U.S. citizens in 

increasing numbers. As they became citizens, 

they could sponsor the legal immigration of 

immediate relatives without being subject to 

numerical limits. We deemed this flow, 

composed largely of people from Mexico and 

Central America, to be somewhat transitory. 

Hence, migration from this source is projected to 

reach a peak early in the decade of 2000 to 2010, 

then gradually decline to zero as the supply of 

potential reunifications is exhausted. In 

particular, legal migration from Mexico is 

assumed to return to the levels of the early 1990's 

by 2010. 

2) We assume that there will be no change in 

immigration policy which would result in any 

change in the quantity of immigrant visas 

available in numerically limited legal categories 

between 1998 and 2020. Numerically limited 

categories embrace all legal immigration except 

for the adjustment of refugees and asylees to 

immigrant status, the admission of immediate 

relatives of U.S. citizens, and a few other 

categories of little demographic consequence. 

3) The flow of refugees to permanent residence in 

the U.S. would tend to decline between 1998 and 

2020, except for a near-term increase to 2000 in 

the number of refugees from the republics of the 

former Yugoslavia. The decline in the flow from 

the principal sources of the last 30 years, 

Southeast Asia and Cuba, is apparent in the 

current refugee data series from 1995 forward. 

The trend from the former Yugoslavia has been 

sharply upward since 1991, although the timing 

and the height of the peak in this trend will 

depend on the course of world events, as well as 

the direction of United States refugee 

resettlement policy. 

4) Undocumented migration of people born in 

Mexico and Central America is viewed primarily 

as a function of the degree of success in 

controlling the southwest border, and is not 

projected to change from levels assumed for the 

1990's base series. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 18 

5) Legal migration from places other than 

Mexico, Central America, and refugee sources 

will vary in trend, depending on recent 

observations, and, to a lesser extent, the 

perceived demographic capacity of the source 

countries to supply migrants. The emerging 

sources of migration that continue to increase in 

importance under this assumption are South 

Asia, Sub-Saharan Africa, and the Middle East. 

We project a modest decline for the Philippines, 

and little change in the influx from other areas. 

A summary of the numerical assumption for 

migration to the United States used for the middle 

series is excerpted in Table E, together with the 

current trend from 1991 to 1998. The first block 

of this table, showing the middle series 

assumption, indicates a modest rise in inmigration from 1,234,000 in 1998 to 1,272,000 

in 2002, a decline to 1,036,000 by 2010, 

followed by a gradual rise to 1,090,000 by 2020. 

The rise and decline are propelled mainly by the 

previously postulated trends from Mexico 

(IRCA-related family reunifications) and the 

former Yugoslavia (refugee movements), while 

the subsequent rise is dominated by the relatively 

more gradual trends from the emerging sources 

identified in point 4 above. 

Projection of the Level of In-Migration: 

Middle Series, 2021 to 2100 

For the period from 2021 to 2100, the focus of 

the projection of migration into the U.S. shifts 

from the individual consideration of various 

sources of migration from abroad to the trend in 

the aggregate level. The projection of migration 

by source region follows, but only with the aim 

of establishing a distribution that can be used to 

impute demographic characteristics. The 

principal assumptions are as follows, and are 

reflected, once again, in the first block of 

Table E. 

1) Driven by a rapid increase in the dependency 

ratio (number of people in the traditionally 

dependent age groups, under 15 years and 65 

years and over, relative to the balance of the 

population), migration to the U.S. would increase 

from 2020 to 2030, from a level of 1,090,000 in 

2020 to 1,450,000 in 2030. 

2) From 2030 to 2100, migration into the United 

States would remain numerically constant at 

1,450,000, even in the presence of an increasing 

population, hence, its direct proportional impact 

on the population would decline. 

The phenomenon underlying the projected 

increase through the 2020's is a pervasive one in 

all considerations of the future demographic 

characteristics of the United States. The historic 

rise in births that occurred in the United States 

from 1946 through the 1950's, followed by the 

decline through the early 1970's, left a bulge in 

the age distribution that has ensured an 

unnaturally low dependency burden through the 

1980's and 1990's on into the early 2010's. 

Table F shows the trend in population, the 

dependency ratio, and the elderly dependency 

ratio (defined as the ratio of people aged 65 and 

over to people in ages 15 to 64), under various 

migration assumptions. In the complete absence 

of migration in or out of the United States from 

1999 onward (“zero migration,” in Table F), the 

dependency ratio rises from 53.0 percent in 2015 

(close to the current level) to 69.4 percent by 

2030, while the elderly dependency ratio endures 

a near parallel rise from 23.5 to 37.1. Our 

projections anticipate an increase in the influx of 

migrants to the United States as a response to 

this dramatic downward shift in the availability 

of potential workers relative to people outside the 

normal working ages. The anticipated increase, 

from 1,090,000 to 1,450,000 annually, while 

large in percentage terms (33 percent) is modest 

relative to shifts that have occurred in migration 

in the United States and elsewhere in the 

industrialized world in response to economic and 

demographic shifts of this importance. The 

migration response to the economic boom of the 

1920's in the United States, and the labor 

migration from southeastern to northern Europe 

in the period following World War II are 

examples of migratory shifts far more dramatic 

than the one projected here. On the other hand, 

to project a much larger shift (for example, a 

U.S. Census Bureau January 2000 
U.S. National Projections 19 

shift comparable to what the U.S. experienced in 

the early 20th century) would tend to overlook the 

possibility of restrictive policies intended to limit 

such a shift. 

The impact of this projected migration trend on
 

the dependency ratio, while not impressive,
 

should be of some significance in the long-term. 

In the zero migration model (first block,
 

Table F), the dependency ratio increases from
 

58.1 percentage points, to 69.4, an increase of 

11.3 percentage points, from 2020 to 2030. 

Under the middle-series migration assumption, it 

increases from 57.2 percentage points to 65.9, up 

8.7 percentage points during the same period. 

Migration to the U.S. by Race and Hispanic 

Origin 

As previously indicated, the projection 

methodology makes use of the distribution of 

international migration by country of birth in the 

base year, distinguishing among major regions of 

the world in establishing the trend. This fact is 

most reflected in the resulting distribution of 

international migration by age, sex, race, and 

Hispanic origin. In the projection of in-migration 

from 1999 to 2020, projections are determined 

primarily by current trends by country of birth, 

with consideration of the legal bases of 

migration. In the projections from 2021 to 2100, 

the international population projections of the 

International Program Center (IPC) of the 

Census Bureau are tapped for information on the 

relative projected growth of the working-age 

component of the population of various world 

regions to the year 2050.37 These projections 

show considerably more rapid population growth 

through the early part of the next century for 

countries of South Asia, sub-Saharan Africa and 

the Middle East, than for countries of the 

Western Hemisphere including Mexico, which 

have seen considerable declines in fertility in 

recent years. 

37 U.S. Census Bureau, International Program Center; 

International Data Base (IDB); <http://www.census.gov/ipc/www 

/idbnew.html>; (11 January 1999) 

The strategy in these projections was to allow the 

composition of international migrants by race and 

Hispanic origin to reflect the probable 

contribution of the various world regions to the 

level of in-migration to the United States 

dynamically. The resulting percentage 

distribution by race and Hispanic origin for the 

middle series is shown in Table D, middle block, 

for selected years in the series. The declining 

contribution of the Western Hemisphere and 

Europe, and the industrialized countries of East 

Asia are reflected in decreasing levels of inmigration for the Hispanic and White 

populations. The increasing contribution of the 

Middle East, South Asia, Southeast Asia, China, 

and sub-Saharan Africa are reflected in increased 

migration for the Black and API populations. 

Low and High International Migration 

Assumptions 

The objective in projecting low and high variants 

for the international migration assumption is to 

establish a candid view of the uncertainty 

surrounding the middle series projection. Three 

qualitative considerations governed the choice of 

the upper and lower limits for in-migration. 

1) The margin of uncertainty around the middlelevel assumption is, of necessity, relatively wider 

for international migration than for births and 

deaths. The exogenous character of this 

component, and its reliance on unpredictable 

external factors such as the internal policy 

environment and world events, as well as the lack 

of demographic determinism in its projection, 

ensure a comparatively high level of uncertainty 

for this component. 

2) The displacement between high, middle, and 

low variants should increase over time, as it did 

for both fertility and mortality. Uncertainty in 

any component increases along with the elapsed 

time from the relatively certain present to any 

projected reference date. 

3) The pace of the increase in the spread between 

high and low should decrease over time. While 

somewhat less obvious, this follows from the 

U.S. Census Bureau January 2000 
U.S. National Projections 20 

goal to reflect uncertainty in the population 

series. The population series is most affected by 

cumulative, rather than current levels of 

international migration. Because some of the 

error in the middle series migration assumption 

should be caused by fluctuations in the level of 

migration, rather than long-term trends, a portion 

of it can be expected to wash out with the 

passage of time. Similar reasoning was applied 

to the projection of the low and high variants of 

fertility, where fluctuations over time are also 

expected. This effect was not considered 

important in the projection of mortality. 

4) We assume that the difference between high 

and middle assumptions will exceed the 

difference between low and middle assumptions. 

Specifically, we assume that the differences in 

the logarithms of the three series (high minus 

middle, middle minus low) are equal. This is 

equivalent to saying that the series are equidistant 

in a multiplicative sense, or that the ratios of high 

to medium equal the ratios of medium to low. 

This follows from the nature of the theoretical 

upper and lower bounds. We can presume that 

the theoretical high-end constraints on gross inmigration are defined only by the population of 

the rest of the world, and can thus be ignored 

(treated as infinity), while the low-end constraint 

is zero. We discount the fact that some outmigration of illegal residents, temporary 

residents, and people moving to Puerto Rico are 

included in our definition of in-migration, 

previously described, on the assumption that 

these elements are small relative to in-migration 

as a whole. A similar reasoning would not apply 

to fertility and mortality, because the 

determinants of their variability above and below 

the middle assumption are presumed comparable. 

To establish the high variant, we assumed a 

deviation from the middle series of zero in 1998 

(since this was the base year), 75 percent in 

2010, and 150 percent in 2100. Multipliers 

applied to the middle series were thus 1.00 for 

1998, 1.75 for 2010, and 2.50 for 2100. A 

logarithmic function was fitted to these three 

multipliers to produce an annual series. We 

established the low variant by computing the 

reciprocal of these multipliers: 1.00 for 1998, 

0.57 for 2010, and 0.40 for 2100, which 

amounted to reducing the middle series by 

43 percent (actually 3/7) in 2010, and 60 percent 

in 2100. 

At its most extreme, the implied range for 

international migration to the U.S. in 2100 was 

from 580,000 migrants to the U.S. to 3,625,000, 

with the middle-level assumption at 1,450,000. 

In 2010 (the low point in the middle series), the 

low, high, and middle values were, respectively, 

592,000, 1,812,000, and 1,036,000. Data for 

these and other selected dates in the series are 

shown in Table E. 

In reviewing the extreme variants for their 

plausibility (albeit as extreme assumptions), we 

also considered their impact on population size 

and dependency ratios over the period of the 

projections. We projected the population using 

each of the three migration assumptions and 

equal values for fertility and mortality rates. 

These results are shown in Table F. The results 

for dependency ratios show a spread between the 

low and high migration series of 1.3 percentage 

points in 2020, increasing to 4.3 points by 2030, 

after the projected increase (reflected in all three 

series) of the 2020's. The spread increases to 6.2 

percentage points by 2100. For total resident 

population, the three models produce levels of 

437 million, 571 million, and 854 million, 

respectively, in 2100. The long-term spread in 

the dependency ratio between high and low 

appears comparatively modest, and changed very 

little over the last 70 years of the projection 

period. This is explained by the fact that many 

of the larger numbers of annual migrants entering 

under the high assumption have dependent 

children and age out of the working life span 

during the period of the projections, thereby 

reducing the difference in the dependency ratio. 

The differences in population are indeed stark, 

with the high-migration assumption yielding near 

double the population produced by the lowmigration assumption in 2100. International 

migration may address a high dependency ratio 

U.S. Census Bureau January 2000 
 

U.S. National Projections 21 

decisively in the short-term, yet is highly 

inefficient in reducing it over the longer term-­

especially if considerations of population scale, 

as well as age composition, are taken into 

account. 

Projection of Emigration of Legal U.S. 

Residents 

As previously indicated, emigration of legal 

foreign-born residents is projected on the basis of 

age-sex-specific rates, applied to a population at 

risk, rather than a postulated numerical trend. 

Current values of these rates were developed on 

the basis of research conducted by the Census 

Bureau.38 The underlying method involves 

computing a matrix of differences between the 

number of foreign-born people enumerated in the 

1980 census, and the number of foreign-born 

people arrived before 1980 enumerated in the 

1990 census. This calculation is carried out for 

large groupings of country of birth, age, and sex, 

an adjustment is made for residents who died 

during the decade, and the balance is assumed to 

be the number of emigrants. Considerable 

modification of the numbers had to be carried out 

because of problems such as negative differences 

for some countries of birth (theoretically 

impossible, but for misreporting on the census) 

and allowances for differential reporting of 

undocumented residents in the two censuses. 

When these distributions are divided by an 

interpolated mid-decade population, they produce 

a schedule of rates, which, when applied to the 

foreign-born population, produce a projection of 

emigration. Unlike the case of in-migration, this 

projection method also produced the results in the 

base series from 1990 to 1998, since no current 

data on foreign-born emigration are available. 

For the middle series, we assumed that foreignborn emigration rates remained constant 

throughout the duration of the projections. This 

means that trends in emigration are driven mainly 

by the size of the foreign-born population, and 

secondarily by its composition by age, sex, and 

country of birth. As shown in Table G, the agesex-country-standardized rate (standardized on 

the 1990 base population) is set at 12.1 per 

thousand population. 

Native emigration was estimated as a constant 

for the base series and the middle series, at 

48,000 per year. This assumption is based on 

research employing reports of U.S.-born 

respondents in foreign censuses, as well as some 

imputation for countries of destination for which 

no such data were available.39 

As shown in Table E, these two assumptions 

yield an annual emigration trend from 252,000 in 

1991, to 278,000 in 1998, the base year for the 

projections. This increases steadily with the 

increase in the foreign-born population, to a level 

of 524,000 in the year 2100. The juxtaposition 

of constant in-migration with increasing 

emigration throughout the last 70 years of the 

next century, presumes a decline in the numerical 

level of annual net migration to the United States, 

and an even greater decline in the impact of this 

component relative to overall population size. 

Low and High Emigration Assumptions 

The extreme variants of foreign-born emigration 

rates are based on the same logic underlying the 

derivation of the extreme variants of inmigration, except that the application was to 

rates, rather than numbers. Because higher 

emigration implies lower net migration, the highlevel multipliers were used to determine the 

emigration rates used for the low migration 

series, and the reverse was true for the high 

migration series. Because emigration in a given 

year in the middle series was on the order of 1.2 

percent of the foreign-born population, the upperlevel constraint of 100 percent was assumed to be 

infinity, while the lower-level constraint was 

38 Bashir Ahmed and J. Gregory Robinson, Population 

Division, U.S. Census Bureau, “Estimates of Emigration of the 

Foreign-born Population: 1980-1990,” Working Paper No. 9, 1994. 

39 Edward Fernandez, Population Division, U.S. Census 

Bureau, “Estimation of the Annual Emigration of U.S. Born People 

by Using Foreign Censuses and Selected Administrative Data: Circa 

1980,” Working Paper No. 10, 1995. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 22 

zero. Thus, the multiplicative approach to 

producing the extreme variants was deemed 

appropriate. Low-migration foreign-born 

emigration rates for 2010 were obtained by 

multiplying the middle-series by 1.75, while the 

multiplier for 2100 was 2.50. The multipliers for 

the high-migration series were the reciprocals of 

the multipliers for the low-migration series. The 

results are shown in Table G. 

The fact that foreign-born emigration is driven by 

projected rates, rather than projected numbers, 

allows a crossover in numerical emigration 

among the three series, around 2055. In the early 

years of the projections, from 1999 to 2054, the 

numerical level of emigration is higher for the 

low-migration series than for the high-migration 

series. From 2055 to 2100 the reverse is true, 

since the larger size of the foreign-born 

population in the high-migration series relative to 

the low-migration series overcomes the effect of 

the lower emigration rates for the foreign-born in 

the high migration series. 

The derivation of native-born emigration for the 

high and low assumptions follows essentially the 

same logic as that used to derive high and low 

variants for gross in-migration. Multipliers that 

increase (for the high assumption) or decrease 

(for the low assumption) logarithmically are 

applied to the middle series assumption of 48,000 

per year. 

Net Migration of U.S. Citizens 

The net migration of U.S. citizens (aside from 

emigrants who depart the U.S. permanently) is a 

small component of population change that tends 

to be driven primarily by the movement of U.S. 

military personnel between the U.S. and abroad. 

Because it is dominated by military movement, 

this migration is highly dependent on the future 

course of world events. Because of the 

impossibility of projecting such developments, 

we adopt a conservative strategy in projecting 

this component. The overseas population of 

military and dependents is held at a constant 

level, with a constant distribution by age, sex, 

race, and Hispanic origin. Migration is therefore 

equal to the number of overseas births, minus the 

number of overseas deaths, plus the balance of 

net inductions and discharges to the military from 

the overseas population. The age distribution of 

this flow is based on the characteristics of net 

migration required to counteract the natural aging 

of each category of sex, race, and Hispanic origin 

in the overseas population. No high and low 

variants were determined for the net migration of 

U.S. citizens. 

SUMMARY 

In developing population projections for the 

United States, we have made a number of 

decisions regarding the scope of the projections 

and the assumptions that were somewhat 

“bolder” than those adopted in most previous 

series. The boldest decision was undoubtedly the 

one to extend the series to the year 2100. In 

making this decision, we were fully aware of the 

precarious nature of any population projection 

that is three human generations past the existing 

population base. While the trend over the first 

20 years of a projection series is generally 

dominated by the characteristics of the base 

population in demographic projections, 

populations for dates 50 to 100 years in the 

future are highly subject to behavioral decisions 

by individuals, policy decisions by governments 

at home and abroad, and possible unexpected 

developments in health and morbidity. In 

formulating assumptions for the highest and 

lowest series that are progressively extreme, we 

have attempted to convey a sense of the caution 

with which any such long-term projections should 

be interpreted. 

Another area of innovation in these projections is 

in the projection of international migration. Once 

again, we recognize the uncertainty about the 

future course of migration that has tended to 

motivate simpler, more parsimonious 

assumptions in the past. Yet, we decided that 

this component of change had received enough 

public attention in recent years that we could not 

U.S. Census Bureau January 2000 
U.S. National Projections 23 

credibly assume it to be unaffected by 

demographic changes in the population, as the 

constant-level projection tacitly assumes. 

Projecting the human population continues to be 

an evolving science, and we fully expect that 

future developments, including the upcoming 

2000 census, will provide us with the basis to 

revise these assumptions in future years. 

U.S. Census Bureau January 2000 
 

 

U.S. National Projections 24 

Table A. Comparison of Total Population, Present Series with 1994-Based Projections. 

(Numbers in thousands. As of July 1. Resident population.) 

Year 

Population Average Annual Percent Change 

Lowest Series Middle Series Highest Series Lowest Series Middle Series Highest Series 

1994-Based Projections1 

1998 268,396 270,002 271,647 -­ -­ -­

2000 271,237 274,634 278,129 0.53 0.85 1.18 

2025 290,789 335,050 380,781 0.28 0.80 1.26 

2050 282,524 393,931 518,903 -0.12 0.65 1.24 

2100 -­ -­ -­ -­ -­ -­

New Series (1998-Based) 

1998 2 270,299 270,299 270,299 -­ -­ -­

2000 274,853 275,306 275,816 0.84 0.92 1.01 

2025 308,229 337,815 380,397 0.46 0.82 1.29 

2050 313,546 403,687 552,757 0.07 0.71 1.49 

2100 282,706 570,954 1,182,390 -0.21 0.69 1.52 

1 Jennifer Cheeseman Day, U.S. Bureau of the Census, Population Projections of the United States by Age, Sex, Race, and Hispanic 

Origin: 1995 to 2050 , Current Population Reports, P25-1130, U.S. Government Printing Office, Washington, DC, 1996. 2 Consistent with population estimates produced by the Bureau of the Census in 1998. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 25 

Table B. Projected Total Fertility Rates by Race and Hispanic Origin, 1999 to 2100. 

(Rates per 1,000 women. As of July 1. Resident population.) 

Race and Hispanic Origin Lowest Series Middle Series Highest Series 

1999 2025 2050 2100 1999 2025 2050 2100 1999 2025 2050 2100 

Total Fertility Rate 

Total 2,035.8 1,865.5 1,799.7 1,632.1 2,047.5 2,206.8 2,219.0 2,182.9 2,059.2 2,557.5 2,646.8 2,737.4 

White, Non-Hispanic 1,822.9 1,725.5 1,668.8 1,552.5 1,833.0 2,030.0 2,043.3 2,070.0 1,843.2 2,334.5 2,417.9 2,587.5 

Black, Non-Hispanic 2,066.9 1,802.0 1,725.9 1,575.0 2,078.4 2,120.0 2,113.3 2,100.0 2,090.0 2,438.0 2,500.8 2,625.0 

American Indian, Non-Hispanic1 2,407.2 1,929.5 1,823.9 1,620.1 2,420.6 2,270.0 2,233.3 2,160.0 2,434.1 2,610.5 2,642.8 2,699.9 

Asian, Non-Hispanic2 2,216.6 1,845.5 1,759.5 1,590.9 2,229.0 2,171.2 2,154.5 2,121.2 2,241.4 2,496.9 2,549.5 2,651.4 

Hispanic Origin3 2,904.3 2,275.7 2,092.9 1,750.4 2,920.5 2,677.3 2,562.8 2,333.8 2,936.7 3,078.9 3,032.6 2,917.2 

White 1,998.0 1,867.4 1,806.5 1,640.3 2,009.5 2,210.2 2,230.1 2,198.0 2,021.0 2,563.9 2,667.5 2,764.5 

Black 2,110.1 1,836.7 1,760.4 1,598.8 2,121.9 2,164.1 2,159.1 2,131.0 2,133.8 2,493.5 2,558.6 2,663.6 

American Indian1 2,492.5 2,003.9 1,893.5 1,663.9 2,506.6 2,366.3 2,329.4 2,224.3 2,520.8 2,736.1 2,774.9 2,791.3 

Asian2 

2,264.9 1,877.8 1,785.5 1,603.8 2,277.4 2,205.8 2,180.8 2,134.7 2,289.9 2,531.4 2,573.8 2,664.6 

1 "American Indian" is used to describe the American Indian, Eskimo, and Aleut population.
 

2 "Asian" is used to describe the Asian and Pacific Islander population.
 

3 Hispanic origin may be of any race.
 

U.S. Census Bureau January 2000 
 

U.S. National Projections 26 

Table C. Projected Life Expectancy at birth by Race and Hispanic Origin, 1999 to 2100. 

(As of July 1. Resident population.) 

Race and Hispanic Origin Lowest Series Middle Series Highest Series 

1999 2025 2050 2100 1999 2025 2050 2100 1999 2025 2050 2100 

Life Expectancy at Birth (Years) 

Total Population (Male) 74.0 76.5 79.5 85.0 74.1 77.6 81.2 88.0 74.1 79.1 83.8 92.3 

Total Population (Female) 79.7 82.6 84.9 89.3 79.8 83.6 86.7 92.3 79.8 84.6 88.4 95.2 

White, Non-Hispanic (Male) 74.7 76.9 79.5 84.8 74.7 77.8 81.1 87.6 74.7 79.2 83.5 91.8 

White, Non-Hispanic (Female) 80.1 82.6 84.8 89.0 80.1 83.6 86.4 91.8 80.1 84.5 88.0 94.6 

Black, Non-Hispanic (Male) 68.3 72.4 76.6 83.9 68.4 73.6 78.5 86.9 68.5 75.3 81.3 91.4 

Black, Non-Hispanic (Female) 75.1 79.3 82.7 88.4 75.1 80.5 84.6 91.5 75.2 81.7 86.5 94.5 

American Indian, Non-Hispanic (Male)1 72.8 77.2 80.3 85.6 72.9 78.4 82.2 88.5 73.0 80.1 84.9 92.9 

American Indian, Non-Hispanic (Female)1 82.0 85.3 87.3 90.6 82.0 86.5 89.2 93.6 82.1 87.7 91.0 96.5 

Asian, Non-Hispanic (Male)2 80.8 81.5 83.2 86.6 80.9 82.4 84.8 89.4 80.9 83.8 87.1 93.5 

Asian, Non-Hispanic (Female)2 86.5 86.8 88.1 90.7 86.5 87.7 89.7 93.4 86.6 88.7 91.2 96.2 

Hispanic Origin (Male)3 77.1 79.0 81.4 85.8 77.2 80.0 83.0 88.6 77.2 81.5 85.5 92.9 

Hispanic Origin (Female)3 

83.7 85.1 86.8 90.1 83.7 86.1 88.4 92.9 83.8 87.1 90.0 95.6 

1 "American Indian" is used to describe the American Indian, Eskimo, and Aleut population.
 

2 "Asian" is used to describe the Asian and Pacific Islander population.
 

3 Hispanic origin may be of any race.
 

U.S. Census Bureau January 2000 
 

U.S. National Projections 27 

Table D. Projected Migration by Race and Hispanic Origin, 1999 to 2100. 

(Numbers in thousands.) 

Race and Hispanic Origin Lowest Series Middle Series Highest Series 

1999 2025 2050 2100 1999 2025 2050 2100 1999 2025 2050 2100 

Yearly Net Migration 

Total 739 183 169 117 954 912 984 926 1191 2268 2812 3039 

White 459 59 43 5 588 451 448 374 735 1121 1262 1196 

Black 93 28 24 14 120 139 155 147 153 367 485 561 

American Indian1 6 1 1 1 8 6 7 6 9 14 17 18 

Asian2 180 94 101 98 238 315 374 398 294 765 1048 1264 

Hispanic3 384 86 79 67 468 303 297 264 567 693 748 712 

White, Non-Hispanic 109 -18 -28 -55 161 180 184 136 218 499 594 555 

Black, Non-Hispanic 71 22 18 9 93 118 133 130 119 317 430 512 

American Indian, Non-Hispanic1 1 0 0 0 2 2 3 3 2 5 7 9 

Asian, Non-Hispanic2 

Migration to the U.S. 4 

174 92 99 96 229 309 368 392 285 752 1033 1250 

Total 1065 628 643 580 1236 1270 1450 1450 1435 2569 3271 3625 

White 670 334 314 246 771 655 685 597 893 1280 1474 1415 

Black 131 92 103 106 153 196 244 275 181 419 582 723 

American Indian1 8 4 4 3 9 8 8 8 10 15 18 19 

Asian2 256 198 222 225 304 411 513 569 351 855 1197 1468 

Hispanic3 455 170 149 115 530 364 359 315 620 740 802 761 

White, Non-Hispanic 257 183 183 145 290 331 366 316 329 618 758 731 

Black, Non-Hispanic 102 79 90 96 120 169 216 253 142 365 521 669 

American Indian, Non-Hispanic1 2 1 2 2 2 3 4 4 2 6 8 10 

Asian, Non-Hispanic2 

Emigration of Legal Residents 5 

248 195 219 222 294 403 505 562 341 841 1181 1453 

Total 326 445 474 463 282 358 466 524 244 301 459 586 

White 211 274 272 242 183 205 237 223 158 159 211 218 

Black 38 64 79 92 33 56 89 128 28 52 97 162 

American Indian1 1 2 2 2 1 1 2 2 1 1 2 2 

Asian2 76 104 122 127 66 96 139 171 57 90 149 204 

Hispanic3 71 84 70 49 62 62 63 51 53 46 55 49 

White, Non-Hispanic 149 200 211 200 129 151 183 180 111 119 164 176 

Black, Non-Hispanic 31 56 72 87 27 50 82 122 23 47 91 157 

American Indian, Non-Hispanic1 1 1 1 1 1 1 1 1 0 1 1 1 

Asian, Non-Hispanic2 

74 102 120 126 64 94 137 170 56 89 148 203 

1 "American Indian" is used to describe the American Indian, Eskimo, and Aleut population. 

2 "Asian" is used to describe the Asian and Pacific Islander population. 

3 Hispanic origin may be of any race. 

4 Migration to the U.S. is net of the departures of illegal residents and temporary residents, as well as departures to Puerto Rico. 

5 Emigration of legal residents excludes departures of illegal residents and temporary residents, as well as departures to Puerto Rico. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 28 

Table E. Major Components of Net International Migration to the United States, 1991 to 2100. 

(Numbers in thousands. As of July 1. Resident population.) 

Year 

Lowest Series Middle Series Highest Series 

Net Migration In 2 Out 2 Net Migration In 2 Out 2 Net Migration In 2 Out 2 

Estimates 1 

1991 -­ -­ -­ 664 916 252 -­ -­ -­

1992 -­ -­ -­ 824 1,078 254 -­ -­ -­

1993 -­ -­ -­ 805 1,063 258 -­ -­ -­

1994 -­ -­ -­ 747 1,008 260 -­ -­ -­

1995 -­ -­ -­ 853 1,116 263 -­ -­ -­

1996 -­ -­ -­ 857 1,124 267 -­ -­ -­

1997 -­ -­ -­ 954 1,227 273 -­ -­ -­

1998 

Projections 

-­ -­ -­ 956 1,234 278 -­ -­ -­

1999 739 1,065 326 954 1,236 282 1,191 1,435 244 

2000 624 983 358 964 1,251 287 1,363 1,593 231 

2001 550 932 382 974 1,267 293 1,497 1,722 225 

2002 491 890 400 974 1,272 298 1,594 1,818 224 

2003 422 835 413 939 1,243 303 1,624 1,849 225 

2004 365 788 423 905 1,213 308 1,639 1,866 227 

2005 317 748 430 872 1,184 311 1,645 1,874 229 

2010 149 592 442 713 1,036 322 1,571 1,812 242 

2015 130 570 440 734 1,063 329 1,726 1,982 256 

2020 120 558 438 751 1,090 339 1,854 2,127 274 

2025 182 628 446 912 1,270 358 2,269 2,569 301 

2030 233 696 463 1,061 1,450 389 2,680 3,020 340 

2050 166 643 477 984 1,450 466 2,814 3,271 456 

2100 113 580 467 926 1,450 524 3,047 3,625 578 

1 Population estimates produced by the Bureau of the Census in 1998. 

2 "In" is actually the net of in-migration from all sources and the out-migration of

 undocumented residents, persons moving to Puerto Rico, and temporary legal

 residents returning home. "Out" refers to the emigration of permanent legal

 residents to destinations other than Puerto Rico. 

U.S. Census Bureau January 2000 
 

U.S. National Projections 29 

Table F. Population and Dependency Ratios per 100 Persons, Four Series, 1990 to 2100. 

(Numbers in thousands. As of July 1. Resident Population.) 

Year 

Zero Migration Series Lowest Migration Series Middle Series Highest Migration Series 

Age 65 and 

over and under 

15 2 

Age 65 and 

over 3 

Dependency Ratio 

Population Age 65 and 

over and 

under 15 2 

Age 65 and 

over 3 

Population 

Dependency Ratio 

Age 65 and 

over and 

under 15 2 

Age 65 and 

over 3 

Population 

Dependency Ratio 

Age 65 and 

over and 

under 15 2 

Age 65 and 

over 3 

Dependency Ratio 

Population 

Estimates 1 

1990 -­ -­ -­ -­ -­ -­ 248,765 51.9 19.0 -­ -­ -­

1995 -­ -­ -­ -­ -­ -­ 262,765 53.1 19.6 -­ -­ -­

1998 

Projections 

-­ -­ -­ -­ -­ -­ 270,299 52.1 19.4 -­ -­ -­

2000 273,818 51.5 19.2 274,910 51.4 19.2 275,306 51.3 19.1 275,756 51.3 19.1 

2010 287,710 49.7 20.4 293,438 49.6 20.1 299,862 49.4 19.8 308,668 49.1 19.4 

2015 294,741 53.0 23.5 302,069 52.9 23.0 312,268 52.6 22.5 327,011 52.2 21.7 

2020 301,636 58.1 27.7 310,584 57.7 26.8 324,927 57.2 26.0 346,661 56.4 24.8 

2025 307,923 64.4 32.8 318,817 63.3 31.3 337,815 62.3 30.1 367,912 60.7 28.2 

2030 313,219 69.4 37.1 326,641 67.6 35.0 351,070 65.9 33.2 391,446 63.4 30.5 

2035 317,534 71.3 39.0 333,854 69.0 36.3 364,319 67.0 34.3 416,564 63.9 31.0 

2040 321,167 71.2 39.1 340,510 68.8 36.3 377,350 66.8 34.1 442,528 63.5 30.6 

2045 324,449 70.9 38.8 346,910 68.5 35.9 390,398 66.5 33.8 469,462 63.2 30.2 

2050 327,641 71.2 38.9 353,314 68.8 36.1 403,687 66.9 33.9 497,509 63.5 30.3 

2060 334,724 72.9 40.2 367,135 70.4 37.4 432,011 68.1 35.0 557,864 64.5 31.3 

2070 343,815 73.1 40.7 383,186 70.8 38.1 463,639 68.4 35.4 624,724 64.9 31.9 

2080 354,471 74.1 41.7 400,744 72.1 39.4 497,830 69.6 36.6 697,016 66.2 33.3 

2090 365,689 75.9 43.6 418,845 73.6 41.1 533,605 70.9 38.1 773,579 67.5 34.8 

2100 377,444 77.3 45.2 437,515 74.9 42.6 570,954 72.0 39.5 854,299 68.7 36.2 

1

 Population estimates produced by the Bureau of the Census in 1998.
 

2 The dependency ratio is defined here as the ratio of the population aged under 15 or 65 and over to the population aged 15 to 64 stated as a percentage.
 

3 The elderly dependency ratio is the ratio of the population aged 65 and over to the population aged 15 to 64 stated as a percentage.
 

U.S. Census Bureau January 2000 
 

U.S. National Projections 30 

Table G. Standardized Rates of Foreign-Born Emigration, 1991 to 2100. 

(Rates are per thousand foreign-born persons. As of July 1.) 

Years M igration Series 

Lowest M iddle H ighest 

Estimates 1 

1991 -­ 12.1 -­

1998 -­ 12.1 -­

Projections 

2000 15.4 12.1 9.5 

2005 19.2 12.1 7.7 

2010 21.2 12.1 6.9 

2015 22.6 12.1 6.5 

2020 23.7 12.1 6.2 

2030 25.3 12.1 5.8 

2040 26.4 12.1 5.6 

2050 27.4 12.1 5.4 

2060 28.1 12.1 5.2 

2070 28.8 12.1 5.1 

2080 29.4 12.1 5.0 

2090 29.9 12.1 4.9 

2100 30.3 12.1 4.9 

Note: Rates are standardized by age, sex, and country of origin,

 using the population estimates base distribution of 

April 1, 1990. 

1

 Population estimates produced by the Bureau of the Census in 1998. 

U.S. Census Bureau January 2000 
January 7, 2000 

POPULATION DIVISION WORKING PAPER SERIES 

For copies of these working papers, please contact the Statistical Information Staff, Population Division, 

Bureau of the Census, Washington, DC 20233-8800 (301)457-2422/pop@census.gov 

NO. 1 - "The Census Bureau Approach for Allocating International Migration to States,Counties, 

and Places: 1981-1991." David L. Word. October 1992. 

NO. 2 - "Geographic Coding of Administrative Records–Past Experience and Current Research." 

Douglas K. Sater. April 1993. 

NO. 3 - "Postcensal Population Estimates: States, Counties, and Places." John F. Long. August 

1993. 

NO. 4 - "Evaluating the Passel-Word Spanish Surname List: 1990 Decennial Census Post 

Enumeration Survey Results." R. Colby Perkins. August 1993. 

NO. 5 - "Evaluation of Postcensal County Estimates for the 1980s." Sam T. Davis. March 1994. 

NO. 6 - "Metropolitan Growth and Expansion in the 1980s." Richard L. Forstall and James D. 

Fitzsimmons. April 1993. 

NO. 7 - "Geographic Coding of Administrative Records -- Current Research in ZIP/Sector-toCounty Coding Process." Douglas K. Sater. June 1994. 

NO. 8 - "Illustrative Ranges of the Distribution of Undocumented Immigrants by State." Edward 

W. Fernandez and J. Gregory Robinson. October 1994. 

NO. 9 - "Estimates of Emigration of the Foreign-Born Population: 1980-l990." Bashir Ahmed 

and J. Gregory Robinson. December 1994. 

NO. 10 - "Estimation of the Annual Emigration of U.S. Born Persons by Using Foreign Censuses 

and Administrative Data: Circa 1980." Edward W. Fernandez. January 1995. 

NO. ll - "Using Analytic Techniques to Evaluate the 1990 Census Coverage of Young Hispanics." 

Edward Fernandez. May 1995. 

NO. 12 - "Metropolitan and Nonmetropolitan Areas: New Approaches to Geographical Definition." 

Donald C. Dahmann and James D. Fitzsimmons. October 1995. 

NO. 13 - "Building a Spanish Surname List for the 1990's--A New Approach to An Old Problem." 

David L. Word and R. Colby Perkins, Jr. February 1996. 

NO. 14 - "Fertility of American Men." Amara Bachu. March 1996. 

NO. 15 - "Comparisons of Selected Social and Economic Characteristics Between Asians, 
Hawaiians, Pacific Islanders, and American Indians (Including Alaskan Natives)." Edward 

W. Fernandez. June 1996. 

NO. 16 - "Findings on Questions on Race and Hispanic Origin Tested in the 1996 National Content 

Ethnic and Hispanic Statistics Branch. December 1996. 

for Health Statistics." Larry Sink. February 1997. 

NO. 18 - "Results of the 1996 Race and Ethnic Targeted Test." May 1997. 

1990 Census." David L. Word. July 1997. 

March 1998. 

O’Connell. March 1998. 

the United States" Dianne Schmidley and J. Gregory Robinson. April 1998 

and Kristin Smith. April 1998 

Fields. April 1998 

No. 25 - "Timing of First Births: 1930-34, 1990-94. Amara Bachu. May 1998 

Casper and Ken Bryson. May 1998 

to 1990." Campbell Gibson. June 1998 

Americans?" Loretta E. Bass and Lynne M. Casper. March 1999. 

1990." Campbell J. Gibson. February 1999 

of Income and Program Participation." Kurt J. Bauman. November 1998 

Cross-roads?" Amy Symens. December 1998 

Survey." Prepared in the Population Division by the Racial Statistics Branch and the 

NO. 17 - "Race and Ethnicity Classification Consistency the Census Bureau and the National Center 

NO. 19 - "Who Responds/Who Doesn’t? Analyzing Variation in Mail Response Rates During the 

No. 20 - "Trends in Marital Status of U.S. Women at First Birth: 1930 to 1994." Amara Bachu. 

No. 21 - "State Estimates of Organized Child Care Facilities." Lynne Casper and Martin 

No. 22 - "How Well Does the Current Population Survey Measure the Foreign-Born Population in 

No. 23 - "Poverty, Family Structure, and Child Well-Being: Indicators from the SIPP." Jason Fields 

No. 24 - "Child Well-Being Indicators from the SIPP." Kristin Smith, Loretta Bass, and Jason 

No. 26 - "Co-Resident Grandparents and Grandchildren: Grandparent Maintained Families." Lynne 

No. 27 - "Population of the 100 Largest Cities and Other Urban Places in the United States: 1790 

No. 28 - "Are There Differences in Voting Behavior Between Naturalized and Native-born 

No. 29 - "Historical Census Statistics on the Foreign-born Population of the United States: 1850­

No. 30 - "Direct Measures of Poverty as Indicators of Economic Need: Evidence from the Survey 

No. 31 - "American Community Survey and Intercensal Population Estimates: Where Are the 
 

No. 32 - "Women’s Labor Force Attachment Patterns and Maternity Leave: A Review of the 

Literature." Kristen Smith and Amara Bachu. January 1999 

No. 33 - "Evaluation of Relationship, Marital Status, and Grandparents Items on the Census 2000 

Dress Rehearsal" Charles Clark and Jason Fields. April 1999. 

No. 34 - "Unbinding the Ties: Edit Effects of Marital Status on Same Gender Couples." Charles 

Clark and Jason Fields. April 1999. 

No. 35 - "Racial-Ethnic and Gender Differences in Returns to Cohabitation and Marriage: Evidence 

from the Current Population Survey." Philip N. Cohen. May 1999. 

No. 36 - "How Does POSSLQ Measure Up? Historical Estimates of Cohabitation." Lynne Casper, 

Philip N. Cohen, and Tavia Simmons. May 1999. 

No. 37 - "Childlessness Among American Women On the Rise?" Amara Bachu. May 1999. 

No. 38 - "Methodology and Assumptions for the Projections of the United States: 1999 to 2100" 

Frederick W. Hollmann, Tammany J. Mulder, and Jeffrey Kallan. January 2000. 

No. 39 - "What Do We Know About the Undercount of Children?" Kirsten K. West and J. Gregory 

Robinson. August 1999.