Immigration Replacing Births as Primary Driver of U.S. Population Growth

By Edwin S. Rubenstein
Volume 26, Number 2 (Winter 2016)
Issue theme: "Immigration Briefing Book"

Rising immigration levels, coupled with a declining rate of natural increase (births minus deaths), mean that immigration will soon be the largest driver of U.S. population growth. The latest Census Bureau population projection—published in December 2014—has U.S. population growing by 2.6 million in 2015. Of this total, 1.2 million will be due to net international immigration and 1.4 million will be due to natural increase.

Within ten years these components are expected to change places.


In 2023 net immigration is projected to pass natural increase as the largest factor in U.S. population growth. In that year the influx of foreign-born will add 1.291 million to the U.S. population, exceeding natural increase, which will add 1.279 million. The gap widens dramatically in the 2030s and 2040s, so that by 2050 net international immigration is expected to be five times larger than natural increase: 1.473 million versus 315,000.1

In other words, first-generation immigrants (new arrivals) will account for 82 percent of U.S. population growth in 2050, according to the Census Bureau. In the 1960s this group accounted for only 16 percent of population growth, and as recently as the 2010 to 2014 period, only 40 percent.

In fact, these figures understate the true impact of immigration on U.S. population growth by ignoring the U.S.-born children of immigrant mothers. The omission is significant:


Births to immigrant mothers have quadrupled over the past four decades, from 228,500 in 1970 to 930,135 in 2010. The peak year was 2007, when 1.07 million babies—24.8 percent of all U.S. births—were born to foreign-born mothers. Even in 1910—the peak of the Great Wave—only 21.9 percent of births were to foreign-born mothers, according to a Center for Immigration Studies` report. Of course, back then the native birth rate was much higher than it is today, while immigration was poised to decline—first as a result of World War I, and later due to the moratorium. Illegal immigration was a rarity—a situation generally conducive to assimilation.

Not so today. Births to illegal alien mothers—AKA “anchor babies”—have accounted for as much as 42 percent of all immigrant births. That may sound high until you consider that illegals account for at least one-quarter of the total immigrant population, and a still larger share of foreign-born females in the prime child-bearing years, 18 to 39. Moreover, their fertility rate—average number of births per mother of childbearing age—is higher than that of legal immigrants.

As currently interpreted, the Fourteenth Amend-ment confers American citizenship on anyone born in the U.S.—no matter what is the legal status of the parents. As U.S. citizens, anchor babies can stay permanently, can prevent a parent`s deportation, and when they become adults, can petition to have their illegal alien parent become a naturalized U.S. citizen. In this Alice in Wonderland world today`s illegal immigrants could eventually account for a larger share of the legal foreign-born population than today`s legal immigrants.

The decline in births after 2007 reflects, in part, the reverse migration of illegal aliens to Mexico following the economic turmoil of late 2008. But there is more to it than that. Since 2008 fertility rates have declined across the board, for immigrants and native-born mothers alike:


Birth rates for women in their reproductive years declined more than twice as much for immigrants (legal and illegal combined) than natives between 2008 and 2013. Immigrant women of reproductive age had, on average, 14 fewer births per 1,000 over that period, while U.S.-born women had 5 fewer births per 1,000. (The Census Bureau reports a problem with the fertility rates variable in 2012.)

A different measure of fertility, the Total Fertility Rate (TFR), also fell during this period. The TFR is an estimate of the number of children a woman will have over her reproductive lifetime. As with birth rates, the TFR of immigrants has declined more rapidly than that of natives since 2008. However, immigrant TFRs are projected to remain above the so-called “replacement level” of 2.1 throughout the 2015 to 2060 period. By contrast, TFRs for native-born mothers are expected to remain in the range of 1.6 to 1.8, portending an eventual decline in this population.2

The decline in births to immigrant women is explained by behavior (falling birth rates) rather than population composition (change in the number of women in childbearing ages). A Pew Research Report links the post-2007 birth rate decline to economic distress. States with the largest economic declines from 2007 to 2008 experienced relatively large fertility rate declines from 2008 to 2009, the analysis found. Both foreign- and U.S.-bornHispanic women had larger drops in birth rate than any other group. That correlates with larger percentage declines in household wealth for Hispanics than in white, black, or Asian households.3

Despite the recent birth rate decline, immigrant mothers continue to have a disproportionate share of the nation’s newborns. In 2013 (latest available data), 22.3 percent of all babies born in the U.S. had an immigrant mother. This was higher than the immigrant share of the U.S. population (13 percent), and higher than the 17 percent share of women of childbearing age (15 to 44) who are immigrants.

As the economy improves, and marriage becomes more affordable, it is likely that birth rates will stabilize and eventually rise for immigrants and native-born alike. This may already be happening: Preliminary data for 2014 indicate there were 62.9 births per 1,000 women of childbearing age that year, up from 62.5 births in 2013, and the highest birth rate since 2007. The nearly four million total births in 2014 also represented the most since 2010. The preliminary data do not break out births to immigrant and native-born mothers separately.4

My research indicates that immigrant employment has risen 5.4 times faster than native-born American employment—15 percent versus 2.8 percent—since 2009. This imbalance makes it likely that births to immigrant mothers will account for an increasing share of all U.S. births in coming years.5

The Foreign-Born Population

The foreign-born population, 42.4 million in 2014, is 3 times larger than it was in 1980. In 1910, the peak of the Great Wave, only 13.5 million immigrants lived here. Our total population has grown, of course, but the immigrant share of the U.S. population is currently at levels not seen since before restrictionist legislation was enacted in the 1920s:


The immigrant population share has increased nearly 3 fold since 1970, when it was 4.7 percent. The above chart shows that only in 1900 and 1910 was the foreign-born percentage of population higher than it is today, while it has been lower in every Census since then.

The bars on the chart also demonstrate a dramatic 11.3 million increase in the number of foreign-born between 1990 and 2000, and an equally significant 8.9 million rise between 2000 and 2010. In fact, these figures understate the number of persons entering the United States during those decades.


For the immigrant population to increase by one million means that significantly more than one million new arrivals must enter the country because some immigrants already here return to their homeland each year, and about 250,000 immigrants die annually. Thus, of the 40 million immigrants in the country in 2010, 13.9 million reported to the American Community Survey that they arrived in the U.S. in 2000 or later. That is, 13.9 million immigrants say they arrived here during a decade when the foreign-born population rose by “just” 8.9 million. The gap reflects the fact that roughly 5 million immigrants either died or went home during the 2000 to 2010 decade.6

Over the next 46 years the foreign-born population is expected to grow by another 36 million. (See table below.)

By 2060 19 percent of the U.S. population will be foreign-born, up from 13 percent today. As is brought out below, the number of second-generation immigrants (U.S.-born children of immigrants) is projected to grow faster than the immigrants themselves. By 2065 second-generation immigrants will slightly outnumber the foreign-born population, according to a new Pew Research Center study.7

An Immigration Moratorium

What is an immigration moratorium? In its most extreme form, it is a total cessation of both legal and illegal immigration into the U.S. It is rare that such a proposition is made in this country, and implementing such an extreme measure might prove to be impossible. But for research purposes, a zero immigration scenario is useful. It provides an upper bound to the impact that a restrictionist policy can have on future population growth.

Population growth is complicit in most economic, fiscal, and environmental problems facing the United States. For this reason, it is worth comparing U.S. population growth under two scenarios: current immig-ration policy and a zero immigration policy.

The period 1965 to 2015 is especially interesting in this regard, since it coincides with the resumption of mass immigration. President John Kennedy proposed eliminating the national origins quotas in the early 1960s. Congress complied with his wishes: The Immigration and Nationality Act Amendments of 1965 replaced numerical quotas with a system granting preferences for relatives of U.S. citizens and legal permanent residents.

A massive increase in immigration was never intended. Sen. Edward M. Kennedy, the chairman of the subcommittee that conducted hearings on the bill, pledged:

[O]ur cities will not be flooded with a million immigrants annually. Under the proposed bill, the present level of immigration remains substantially the same…8

What happened? The 1965 law supposedly “capped” legal immigration at 300,000 per year, but the cap was waived for persons who had relatives already living in the United States. The focus on family reunification was little noted at the time, but it triggered the resumption of mass immigration into the U.S. As a result, immigration’s share of population growth today rivals that of “The Great Wave” of mass immigration in the late nineteenth and early twentieth centuries.

Had a 1965 immigration moratorium been passed instead of the 1965 Immigration Act, U.S. population would be considerably smaller today:


The nation’s population grew from 193 million to 324 million between 1965 and 2015, an increase of 131 million, or 67 percent. Had an immigration moratorium been in effect, U.S. population would be 252 million today—72 million less than its current level. This implies that 55 percent of U.S. population growth over the past 50 years was due to immigration—either immigrants who arrived during this period or their U.S.-born children and grandchildren.9


For context, a 72 million reduction equals 22 per-cent of the total U.S. population. It is equivalent to the combined populations of 29 states.

Over the next five decades immigration will account for an even larger share of U.S. population growth. Under our current policy of mass immigration U.S. population will grow to 441 million in 2065 from 324 million today, an increase of 117 million. Under a moratorium, 2065 population would be 338 million, or 103 million less than under current policy. Put differently, 88 percent (103 divided by 117) of U.S. population growth over the next fifty years will be due to immigration—either new arrivals or their U.S.-born descendants.

Interestingly, it is the U.S.-born children of immigrants rather than the immigrants themselves that will drive most of the immigration-related growth over the next 50 years. The number of second-generation immigrants is projected to more than double, from 38 million today to 81 million in 2065. By contrast, the immigrant population is projected to rise by “only” 74 percent, which is still more than double the projected growth for the U.S.-born population (30 percent). ■


1. Census Bureau, Projections of the Population and Components of Change for the United States, 2015 to 2060, Table 1, December 2014. Table 1.

2. Census Bureau, Methodology, Assumptions, and Inputs for the 2014 National Projections, Table 1, December 2014.

3. Gretchen Livingston, U.S. Birth Rate Falls to a Record Low; Decline is Greatest Among Immigrants, Pew Research Center, November 29, 2012.

4 . Neil Shah, Six years after recession, Americans may be poised to deliver a ‘baby bounce’,Wall Street Journal, June 17, 2015. rise?wt.mc_id=email|daily+briefing+headline|dba|db|jun-17-2015

5. Edwin S. Rubenstein, National Data: September Jobs: Immigrants Take All for Second Straight Month, October 4, 2015.

6. Steven A. Camarota, A Record-Setting Decade of Immigration: 2000 to 2010, Center for Immigration Studies, October 2011.

7. Mark Lopez, Jeffrey Passel, and Molly Rohal, Modern Immigration Wave Brings 59 Million to U.S., Driving Population Growth and Change Through 2065, Pew Research Center, September 2015, page 28.

8. Lawrence Auster, The 1965 Immigration Act: Its Intent, Its Consequences.

9. Mark Lopez, Jeffrey Passel, and Molly Rohal, Modern Immigration Wave Brings 59 Million to U.S., Driving Population Growth and Change Through 2065, Pew Research Center, September 2015.

About the author

Edwin S. Rubenstein, a regular contributor to The Social Contract, is president of ESR Research, economic consultants. As a journalist, Mr. Rubenstein was a contributing editor at Forbes and economics editor at National Review, where his “Right Data”column was featured for more than a decade. He is the author of The Earned Income Tax Credit and Illegal Immigration: A Study in Fraud, Abuse, and Liberal Activism.