​US population stability requires immigration — just not too much

The current populations of some 40 countries are expected to be smaller by the mid-century. That group includes China, Germany, Greece, Hungary, Italy, Japan, Poland, Romania, Russia, South Korea, Spain, Thailand, and Ukraine — but not the United States.

The continuing demographic growth of the United States is a striking exception to the declining populations in most developed countries, as well as in many less developed countries. 

Those population declines are projected to be 16 percent in Japan, 12 percent in South Korea, 11 percent in Italy, 8 percent in China and Russia, 7 percent in Spain and 5 percent in Germany. In contrast, America’s population is expected to increase by 17 percent by 2050, according to the Census Bureau.

America will likely continue being the world’s third-largest population for at least several more decades. In 2050, following India at 1.6 billion and China at 1.3 billion, the U.S. population is projected to reach 390 million. Several years later, however, America will be displaced to fourth place, as Nigeria’s rapidly growing population is projected to reach more than 400 million by 2055.

The major explanation behind the projected declines centers on a fertility rate below the replacement level without sufficient compensating numbers of international migrants. Approximately two-thirds of the world’s population of 8 billion now live in a country where the fertility rate is below the replacement level of 2.1 births per woman.

America’s fertility rate fell below the replacement level more than a decade ago and has continued to remain below that level. The U.S. fertility rate in 2021 was 1.66 births per woman, which is slightly above the average fertility rate of 1.53 births per woman in more developed countries.

America’s below replacement level fertility rate is likely here to stay for the foreseeable future. For various economic, social and personal reasons —  including higher education, employment, careers, the costs of child-rearing and lifestyle preferences —  parenthood is being delayed to older ages with fewer births occurring per woman.

The median age of U.S. women giving birth over the past three decades increased from 27 years to 30 years by 2020, the highest on record. The proportion of U.S. adults aged 55 years and older remaining childless is about 16 percent.

In addition, fertility rates declined by almost 43 percent for women between the ages of 20 and 24 and by more than 22 percent for women between 25 and 29. In contrast, the rates increased by more than 67 percent for women between ages 35 and 39, and by more than 132 percent for women between 40 and 44.

Population projections generally assume America’s fertility rate will remain at approximately its current level for the remaining decades of the 21st century. Consequently, international migration is expected to play a significant role in the future growth of America’s population.

By 2030, for example, international migration is expected to reach a demographic milestone or turning point for America, as it is projected to become the primary driver of the nation’s population growth. Also, by that time, the proportion of America’s population who are foreign-born is expected to reach a record high of 15 percent.

Furthermore, the annual net number of international migrants to America in 2040 is expected to be twice as large as the number due to natural growth, i.e., the difference between births and deaths. Also by the mid-century, the net number of international migrants is projected to be nearly three times the number due to natural increase.

In 2020, the number of foreign-born in America reached a historic high of more than 45 million, nearly 14 percent of the total U.S. population. Over the coming four decades, America is expected to receive slightly more than 1 million immigrants annually. If those levels continue as expected, the projected number of foreign-born in America would total more than 69 million by 2060, or about one in six people living in the country at that time. 

Although America represents about four percent of the world’s population, the country has approximately 16 percent of the world’s international migrants. That figure is more than triple the proportion of foreign-born in second place Germany.

Without international migration, America’s population would soon begin to decline in the ways many countries worldwide are now experiencing. 

With zero migration America’s population would begin declining in size by around 2035 and continue its descent throughout the century. By 2060, for example, America’s population with zero migration is projected to have approximately 85 million fewer people than with international migration at slightly more than 1 million annually.

Of course, if international migration to America were to increase substantially as appears to be happening today, the projected U.S. population would be larger in the future. For example, if net international migration were 50 percent higher than levels assumed for the coming decades, then the U.S. population in 2060 would be 447 million, or about 42 million more people than the main population projection.

In addition to legal immigration, unauthorized migration to America is increasing rapidly. The current number of undocumented migrants in the country is no less than 11 million and rising, which is hardly surprising as America is the top destination country among the hundreds of millions of men and women wanting to emigrate.

Also, more than 2 million unauthorized migrants crossed the country’s southern border during the calendar year 2021 and were apprehended or turned themselves in to U.S. authorities. That figure of unauthorized migrants does not include those not stopped or detected. 

Besides unauthorized migration at the southern border, many people visiting America are choosing to overstay their temporary visas hoping to secure employment, integrate into communities and eventually become citizens.

America’s population exceptionalism is clearly not the result of its fertility rate — it is due to the expected future levels of international migration of slightly more than 1 million people annually. 

Yet, despite the increasing demographic contribution of international migration to America’s future, Congress has been unable to pass clear and comprehensive immigration legislation. The U.S. government and its major political parties have politicized international migration to the detriment of America, its inhabitants and its legacy enshrined in the Statue of Liberty as a nation welcoming immigrants and refugees.

Joseph Chamie is a consulting demographer, a former director of the United Nations Population Division and the author of numerous publications on population issues, including his recent book, “Births, Deaths, Migrations and Other Important Population Matters.”