Monthly Census Bureau Data Shows Big Increase in Foreign-Born

Immigrant population (legal and illegal) grew 1.6 million in past year

By Steven A. Camarota and Karen Zeigler on November 2, 2021

An analysis of the Census Bureau monthly Current Population Survey (CPS) by the Center for Immigration Studies shows that after falling for much of 2020, the foreign-born population (legal and illegal), has rebounded dramatically, increasing by 1.6 million between September 2020 and September 2021, which is the most recent data available. Unlike arrival figures for legal immigrants or border apprehension numbers, the CPS provides insight into the number of foreign-born people, also referred to as immigrants, who have actually settled in the United States, reflecting both new arrivals and those who leave or die each year. There is a lot of variation from month to month in the CPS, so any change should be interpreted in light of this variability. But the data shows clear evidence first of a decline in the total immigrant population (legal and illegal) due to Covid-19 restrictions, and then a dramatic increase reflecting the surge of illegal immigration at the southern border, the restarting of visa processing at American consulates overseas, and the return of international travelers more generally in recent months.

Growth in the Immigrant Population. While there is some undercount, particularly of illegal immigrants, the foreign-born in Census Bureau surveys includes all persons who were not U.S. citizens at birth — naturalized citizens, lawful permanent residents, long-term temporary visitors (e.g. guestworkers and foreign students) and illegal immigrants. Growth in the total immigrant population can only be caused by new legal and illegal immigrants arriving from abroad. Births to immigrants in the United States do not add to the foreign-born as all persons born in the United States are considered native-born by definition. New immigration is offset by those immigrants who leave the country each year (previously estimated at nearly one million annually) and natural mortality among the existing immigrant population of roughly 300,000 a year. For the immigrant population to grow, new arrivals must exceed return migration and deaths.

Figure 1 shows the total immigrant population (legal and illegal) from January 2010 to September 2021, along with margins of error. Figure 1 shows that the nation’s immigrant population grew to 45.4 million in September 2021, a 1.6 million increase since September 2020. The recent growth of 1.6 million follows a 1.1 one million decline in the total immigrant population between September 2019 and September 2020. The decline almost certainly reflects the significant reduction in new legal and illegal immigration due to Covid-19 restrictions on international travel, the suspension, for a time, of visa processing at American consulates overseas, and Title 42 expulsions, which allowed the U.S. government to send illegal immigrants apprehended at the border immediately back to Mexico, even if the immigrant was not from that country. All of these factors seem to have significantly slowed the pace of new arrivals into the country. At the same time, some level of outmigration continued during this time period as did natural mortality, causing the total immigrant population to fall through the middle of 2020. Figure 2 shows a year-to-year monthly comparison in the size of the immigrant population. The biggest year-to-year monthly decline was the 1.6 million from March 2019 to March 2020. But the immigrant population fell to its smallest size of 43.8 million in August 2020.

(Click here for a larger version of Figure 1.)

(Click here for a larger version of Figure 2.)

Illegal Immigration. The federal government, as well as outside researchers, have previously estimated that nearly three-quarters of illegal immigrants are Hispanic, so the recent increase in Hispanic immigrants can be seen as an indication that illegal immigration has increased dramatically in the last year. Hispanic immigrants (legal and illegal), accounted for about half of the 1.6 million increase since last September. Figure 3 shows the number of Hispanic immigrants living in the country and Figure 4 shows year-to-year monthly changes in that population. Like the overall foreign-born population, Figures 3 and 4 show that the number of Hispanic immigrants fell dramatically at the high of the Covid-19 epidemic before rebounding dramatically at the end of 2020 and into 2021. This strongly suggests that the dramatic surge in illegal immigration at the southern border since President Biden’s election is showing up, at least in part, in the monthly Current Population Survey.

(Click here for a larger version of Figure 3.)

(Click here for a larger version of Figure 4.)

The Trump Effect. The monthly data also show evidence for a “Trump effect” on immigration — legal and illegal. Our prior analysis of other Census Bureau data shows that during his first three years in office, before Covid-19 hit, growth in the legal and illegal immigrant population slowed, reflecting a decline in new arrivals and a substantial increase in out-migration. The monthly data confirms our prior findings. In his four years in office (January 2017 to January 2021), the foreign-born population grew by 1.6 million, less than half the 3.4 million growth during Obama’s second term (January 2013 to January 2017). Of course, immigration in the last year of the Trump administration was impacted by the Covid-19 epidemic. But looking only at the first three years (January 2017 to January 2020) of Trump’s administration, before Covid, shows the immigrant population grew by one million, compared to three million in the first three years of the second Obama administration (January 2013 to January 2016).

About the Data. It must be remembered that the monthly CPS, while a large sample, still has a relatively large numerical margin of error of roughly ±500,000 for the foreign-born, assuming a 90 percent confidence level. So numerical fluctuations from month to month can be quite large, making it necessary to compare large changes over longer periods of time when drawing conclusions about trends. The margins of error shown in Figures 1 and 3 are based on standard errors calculated using parameter estimates, which reflect the survey’s complex design. Neither the BLS or the Census Bureau has provided parameter estimates for the general population for the monthly CPS, so we use those for the labor force.

It should also be noted that, like virtually all modern surveys, the CPS is weighted to reflect the total population by age, race, sex, and Hispanic origin. Each January the weights used in the CPS, also called population controls, are re-adjusted to reflect updated figures on births, deaths, and net international migration. The update in January 2021 adjusted the size of the U.S. population slightly downward for January 2021 from December 2020, including the number of Hispanics and Asians. This should have reduced growth in the foreign-born slightly. Yet, the CPS still shows growth in the number of immigrants after this adjustment.

Potential Problems with the CPS. The Census Bureau collects the monthly CPS for the Bureau of Labor Statistics (BLS). The BLS reports potential problems with the CPS since March 2020 because of the Covid-19 pandemic. First, interviewers who administered the survey miscoded some respondents as employed when they were on furlough, temporary layoff, or similar situations.

More importantly for the purposes of this analysis, BLS also states that response rates from March 2020 through September 2021 for the CPS were lower than prior to Covid-19, though rates have improved since hitting a low in June 2020. These lower rates increase the sampling error of the survey. It is not known if this problem had any impact on estimates of the foreign-born in the data. However, in June 2020, when the problem was most pronounced, BLS stated that “Although the response rate was adversely affected by pandemic-related issues, BLS was still able to obtain estimates that met our standards for accuracy and reliability.”

The Other Large Census Bureau Survey. The Census Bureau’s annual American Community Survey (ACS), which also identifies immigrants, is much larger than the CPS and is often used to study the foreign-born. Its larger size means that it has smaller margins of error than the CPS. But the ACS only provides annual estimates, and data from the ACS is released much more slowly than data from the CPS. The 2020 ACS has not yet been released. Moreover, the ACS reflects the U.S. population in July of each year, so when the 2020 ACS is released, it should show a decline in the foreign-born between 2019 and 2020, as in the CPS. But the 2020 ACS will not reflect the rebound after July 2020.