The Impact of Immigration on U.S. Population Growth

By Steven A. Camarota on August 2, 2001

Testimony prepared for the U.S. House of Representatives

Committee on the Judiciary

Subcommittee on Immigration, Border Security, and Claims

August 2, 2001

Mr. Chairman and members of the subcommittee: Thank you for offering me the opportunity to testify at this hearing on immigration's impact on population growth in the United States. My name is Steven Camarota and I am Director of Research at the Center for Immigration Studies, a non-profit, non-partisan research organization in Washington that examines and critiques the impact of immigration on the United States. Among its many activities, the Center is a subcontractor to the U.S. Bureau of the Census on an evaluation of the foreign-born data in the Bureau's new American Community Survey.

When the results of the 2000 Census were released in January of this year, many people at the Census Bureau and elsewhere were surprised to learn that the U.S. population grew by 32.7 million people, the largest single-decade population increase in U.S. history. In fact, since 1980, the United States has added 55 million people to its population — the equivalent of the entire population of France. The United States is virtually the only advanced industrialized countries in its rate of population increase. What accounts for this extraordinary increase in population size? The facts are not really in dispute.

Analysis of the latest data indicates that immigration policy has become the determinant factor in U.S. population growth over the last decade. More importantly, without a change in current policy, immigration will continue to drive U.S. population growth throughout the 21st century. I say "immigration policy" rather than just "immigration" because in the discussion that follows it is important to keep in mind that the level of immigration and thus its impact on population growth over the last decade and in the future, reflects policies and choices made by the federal government concerning who may be allowed into the country legally and the level of resources devoted to controlling illegal immigration.

Immigration's Impact on Population Growth in the 1990s

While there are different ways of thinking about immigration's impact on U.S. population growth, the demographic facts are clear. Looking at immigration's impact in the 1990s is a useful starting point because it provides a great deal of insight into the effect of immigration on population growth not only in the immediate past but also in the immediate future. When the full results of the 2000 Census are in, they will almost certainly show a total foreign-born population of between 30 and 31 million. This figure includes both legal and illegal immigrants.1 The Census will also likely show that of the 30-plus million immigrants living in the United States in 2000, between 13 and14 million arrived in the just 1990s. These numbers are extraordinary because they mean that at least 1.3 million immigrants are settling in the United States each year. To put this into historical perspective, during the last great wave of immigration 100 years ago, which itself was a break with the past, about 850,000 people entered the country each year between 1900 and 1910. There can be no doubt that we are in the midst of another great wave of immigration.

The current numbers mean that about 40 percent of the nearly 33 million increase in the size of the U.S. population during the 1990s is directly attributable to the arrival of new immigrants. We know this simply by dividing 13 million (the number of new immigrants) by the total increase in the size of the U.S. population (32.7 million). If the figure is 14 million, the immigration impact is 43 percent. This is just simple division. In addition to their arrival in the United States, immigrants also cause population growth because, like all people, immigrants have children. During the 1990s, immigrant women gave birth to an estimated 6.9 million children.2 If we add together the number of births to immigrants and the number of new arrivals, then immigration during the 1990s is equal to 20 or 21 million or a little less than two-thirds of the nearly 33 million increase in the size of the U.S. population over the last 10 years. In a very real sense, immigration has become the determinant factor in U.S. population growth.

The Impact of Immigration on Population Growth in the Future

We not only have a good idea of immigration's impact on population growth in the 1990s, we can also estimate its likely impact in the future. The most recent Census Bureau projections provide insight into the likely effect of immigration on population growth throughout this century. According to the Census Bureau’s middle-range projections, if current trends continue, the U.S. population will grow to 404 million by 2050. If there were no immigration, these same projections indicate that the U.S. population would be 328 million (76 million fewer) in 2050. This means that immigration will account for about 63 percent of U.S. population growth over the next 50 years. Put another way, immigrants who have not yet arrived, but who will come to this country between now and 2050, will add the equivalent of the combined current populations of California, Texas, and New York State, to the United States over the next 50 years. Of course, if high immigration is allowed to continue, then its impact on population growth will also continue, and the middle-range Census Bureau projections show the United States will reach a total population 571 million by 2100.3 Again, these are the Census Bureau's middle-range projections — that is, they are the most likely. While the Census Bureau does not have a crystal ball, these projections do tell us a couple of things. First, the impact of immigration is enormous, adding perhaps 200 million people to the American population by 2100. Second, even without immigration there will still be significant population growth because we have created what is called "population momentum" by allowing in so many people over the last three decades. Thus we will have a good deal of it even without future immigration.

It is important to realize that the above projections are now widely acknowledged as having been too low because they are based on the results of the 1990 Census. If one projects forward from the 2000 Census, then the size of the U.S. population in 2050 and 2100 will necessarily be much larger because the projection would be based on a much larger starting point. Moreover, the latest Census Bureau projections are also too low because they assumed a level of immigration that we now know is too low. The Census Bureau had previously assumed that legal and illegal immigration would average 1.1 or 1.2 million people annually for much of this century.4 We now know that this is almost certainly incorrect. Current immigration is already 1.3 million people annually, and without a change in policy it will almost certainly increase in the coming decades. It now seems clear that the Census Bureau has also over estimated the number of immigrants who leave the country each year. Analysis of the year-of-entry question from the Current Population Survey, taken each month by the Census Bureau, shows that relatively few people are leaving the country. There is little doubt that if current trends continue, immigration will add to the country by 2050 many more people than the 76 million indicated by the last Census Bureau population projections.

What Are the Effects of Population Growth?

While there should be no real debate about the overall impact of immigration on population growth, there is, and should be, a debate over whether this kind of increase in population is desirable for the country. Below I examine some of the consequences that would seem to be unavoidable if the population continues to grow dramatically. There are clearly benefits from population growth: many advocates of high immigration, for example point, to the increase in equity for owners of real estate and greater opportunities and choices it should create for businesses and consumers. Nonetheless, there are clearly real costs as well:

Sprawl and Congestion

If we accept the admittedly low projections discussed above, which indicate immigration will add 76 million people to the population over the next 50 years, it means that we will have to build something like 30 million more housing units than would otherwise have been necessary, assuming the current average household size. This must have some implications for worsening the problems of sprawl, congestion, and loss of open spaces, even if one makes optimistic assumptions about successful urban planning and "smart growth." A nation simply cannot add nearly 80 million people to the population and not have to develop a great deal of undeveloped land. Can we quantify the role that population growth plays in causing land to become built up, which is a basic definition of sprawl? It turns out that we can. At its simplest level, there are only two possible reasons for an increase in developed land. Either each person is taking up more land, there are more people, or some combination of the two. It's the same with any natural resource. For example, if one wants to know why the United States consumes more oil annually now than it did 20 years ago, it is either because there are more Americans or because each of us is using more oil, or some combination of the two. In the case of sprawl, the natural resource being consumed is land.

If one compares the increase in developed land in the nation's 100 largest urbanized areas between 1970 and 1990, it turns out that the causes of sprawl are split right down the middle between population growth and increases in per-person land consumption. Of course, this is not true in every city, but overall, population growth and increases in per-person land consumption contributed to sprawl in equal proportions.5 While we cannot say with absolute certainty that population growth will continue to cause more and more land to be developed, both past experience and common sense strongly suggest that population growth of this kind has important implications for the preservation of farm land, open space, and the overall quality of life in many areas of the country. Size of the School-Age Population. In the last few years, a good deal of attention has been focused on the dramatic increases in enrollment experienced by many school districts across the country. The Department of Education recently reported that the number of children in public schools has grown by nearly 8 million in the last two decades.6 All observers agree that this growth has strained the resources of many school districts. Increased funding for education at the state, local, and federal levels has barely been able to keep pace with new construction and to prevent class size from growing. While it has been suggested that this increase is the result of the children of baby boomers reaching school age (the so called "baby boom echo"), it is clear from the Current Population Survey (CPS) that immigration policy explains the growth in the number of children in public schools. We know that immigration accounts for the dramatic increase in school enrollment because the CPS not only asks all respondents their age and if they are immigrants, it also asks when they came to live in the United States. In addition, the CPS asks all persons if their parents were immigrants. With this data, it is a very simple matter to estimate the impact of recent immigration on public schools. In 2000, there were about 8 million school-age children (ages 5 to 17) of immigrants who had arrived since 1970. This is equal to all of the growth in the school-age population over in the last 20 years. Thus, immigration accounts for virtually all of the national increase in the school-age population over the last few decades, not the baby boom echo. The children of immigrants account for such a large percentage of the school-age population because a higher proportion of immigrant women are in their childbearing years and because immigrants tend to have more children than natives. More importantly, without a change in immigration policy, the number of children in our already overtaxed schools will continue to grow. The absorption capacity of American public education is clearly an important issue that needs to be taken into account when formulating a sensible immigration policy. Failure to consider this capacity may have very real consequences for public education in the United States.

Size and Scope of Government

As the population grows, the role of government, by necessity, has to grow with it. It is no accident that cities have many more regulations on everything from parking to trash collection than do rural areas. In sparsely populated states like Wyoming, the state legislature meets in regular session only every other year, while California's is the most active in the country. As population size and density grow and people come into greater contact and conflict with one another, the need for government to regulate social interactions almost always increases. By increasing the size of the U.S. population, immigration policy may unavoidably require more and more regulations on the daily lives of Americans.

Dealing with Global Warming

President Bush recently indicated that, although the United States will not ratify the Kyoto treaty on global warming, he does recognize that global warming caused by the burning of fossil fuels is a genuine problem. Whatever we decide to do about this issue, the size of our population will matter a great deal. Because any international agreement we sign to reduce emissions of greenhouse gases will limit total U.S. emissions, not per-person emissions, a larger population will require each individual to cut back more in order to keep total output at some agreed-upon level. Consider the following: If the United States were to try to limit its emission of greenhouse gases to 1.6 billion metric tons annually, the 1990 level, then the average American can produce no more then 5.2 tons of greenhouse gases if our population is 308 million in 2025, as it would be if there was no immigration. However, if the U.S. population grows to 338 million in 2025, as it is projected to do if current immigration trends continue, then per-person emissions will have to be cut back to 4.7 tons per year. Thus in the next two decades, because of population growth, each American will have to cut back 10 percent more on his production of greenhouse gases than would otherwise have been necessary just to keep the country at the same level. It is simple mathematics. In fact, we could easily face a situation in which each individual could cut back significantly on his or her consumption of fossil fuels and yet total consumption would actually rise because the increase in population is more than the decrease in per-persons emissions.

Not only does this situation have important implications for the standard of living in the United States, it may also adversely affect the competitiveness of U.S. industry. Our primary economic competitors, such as Japan and Germany, do not have to deal with rapid population growth as they seek to cut their emissions of greenhouse gases. It is also worth noting that because most immigrants come from developing countries, immigration has the effect of transferring population from the less-polluting parts of the world to the more-polluting parts of the world. Thus even if the highest priority is placed on reducing the emission of greenhouse gases worldwide, immigration is still counterproductive. Dramatic increases in population make dealing with environmental problems more difficult. It would seem there is simply no way around this problem.

Can Immigration Solve the Social Security Funding Problem?

Many advocates of high immigration argue that it can help our nation deal with the problems created by an aging society, including the need to provide funding for the large number of Social Security recipients who are expected when the baby boomers begin to retire. The Census Bureau's latest population projections specifically address this question and state that immigration is a "highly inefficient" means for increasing the proportion of the population who are workers in the long run. According to the report, if immigration remains high, 60 percent of the population will be of working-age in 2050, compared to 58 percent if there is no immigration. Why does immigration have so little impact on the share of the population who are workers? There are three reasons: First, the average immigrant arrives in his late 20s and is actually not that much younger than the average native. Second, the immigrants who enter today will eventually age and add to the size of the elderly population in the future. And it is the future when Society Security faces its funding crisis, not today. If we really wanted immigration to help with the problem then you would need to have little or no immigration right now, wait 15 or so years and then begin allowing in young immigrants. The third reason immigration cannot fundamentally change the ratio of workers to non-workers is because the higher fertility of immigrants means that they significantly increase the number of children in the population, who like the elderly must be supported by others. The simple fact is we must look elsewhere to solve the challenges created by our aging society.


The impact of immigration on population growth is not in dispute. The entrance of 1.3 million legal and illegal immigrants annually cannot help but to grow the nation's population. Rather than debating the exact size of the impact of immigration on population growth, we need a rational debate over whether we want federal immigration policy to grow the U.S. population by tens of millions of people over the next few decades. It is a choice we are making not only for ourselves but for our children and their children. And it is a choice that cannot be undone.

End Notes

1 We know this because the Census Bureau has already re-weighted the March 2000 Current Population Survey to reflect the results of the 2000 Census and found a total foreign-born population of 30.1 million. To this figure one needs to add the 600,000 immigrants living in what the Census Bureau refers to as group quarters, such as prisons and nursing homes. Most of these individuals are not included the CPS because the survey is designed primarily to capture persons in the work force. In 1990 there were 489,000 immigrants living in group quarters, and that number has increased by at least 100,000 over the last 10 years.

2 These figures are for births to all foreign-born women, including those who arrived prior to 1990. These figures are for birth to all foreign-born women, including those who arrived prior to 1990. In the past I have estimated that there were 6.4 million births to immigrant women in the 1990s. This estimate was of children born in the United States to immigrant women during the 1990s and were still living in the United States at the time of the 2000 Census. I have adjusted upward my pervious estimate of 6.4 million based on the results of the re-weighted Current Population Survey.

3 See Methodology and Assumptions for the Population Projections of the United States: 1999 to 2100 Population Division. U.S. Bureau of the Census. Working Paper No. 38. Frederick W. Hollmann, Tammany J. Mulder, and Jeffrey E. Kallan. Table E (page 29) shows the various migration assumptions used in the Census Bureau's population projections. Table F (page 29) reports the results of these assumptions.

4 Methodology and Assumptions for the Population Projections of the United States: 1999 to 2100 Population Division. U.S. Bureau of the Census. Working Paper No. 38. Frederick W. Hollmann, Tammany J. Mulder, and Jeffrey E. Kallan. Table E page 29.

5 Out Smarting Smart Growth: Immigration, Population Growth and Suburban Sprawl. 2001. Center Paper 18. Roy Beck, Leon Kolankiewicz. Center for Immigration Studies. Washington DC. Forthcoming.

6 See A Back to School Special Report On The Baby Boom Echo.

7 Methodology and Assumptions for the Population Projections of the United States: 1999 to 2100 Population Division. U.S. Bureau of the Census. Working Paper No. 38. Frederick W. Hollmann, Tammany J. Mulder, and Jeffrey E. Kallan. Pages 20-21.