April 1997

The United States population grows by nearly 3 million per year, and is currently approaching 270 million. This is about 55,000 per week, or a rate of 1.1 % per year. This growth rate will double the population in less than 64 years.

The explosive character of such growth becomes clear when our current population size is compared to the population of the United States in 1950, which was only 150 million. In other words, it took all of the history of human habitation in what is now the United States of America for the population to grow to 150 million, yet in the 47 years since 1950, nearly 120 million more have been added.

Over 60% of this 3 million a year population growth is a result of immigration, legal and illegal, a share which rises continuously as births to recent immigrants are added to the annual flow of new arrivals. If current trends continue, by mid-century the United States will have approximately one-half billion¹ people and population growth will be still on a steeply upward path.

Of the more than 1.6 million people which immigration added to the United States in 1994, approximately 1 million came as a result of legal immigration. An additional 300,000 or more were a result of net illegal immigration, and the remaining 400,000 to 500,000 resulted from the surplus of births over deaths among the foreign born. The immigrant sector is slightly under 10% of the population but accounts for over 18% of total births.

Immigration's impact on U.S. population is total immigration and births to the foreign born minus emigration of immigrants and immigrant deaths. The native-born account is births to the native born minus deaths and emigration of this sector.

A calculation of the results of this approach for the year 1994, using National Center for Health Statistics (1996) figures on births and deaths, and Center for Immigration Studies (1995) figures on immigration, yields startling results: immigration and children born to the foreign-born sector account for 60% of annual U.S. population growth.

Table 1. Components of U.S. Population Growth, 1994.

The comparable figures for 1995 show that the immigrant share of U.S. population growth increased to 62%.

Table 2. Components of U.S. Population Growth, 1995.

The remaining component of U.S. population growth is the greater number of births than deaths or emigration among native-born Americans. There are 70 million women from the "baby boom" generation now in their child-bearing years, so even though the average fertility rate of these women is 1.8 (i.e., below replacement level), the phenomenon of demographic momentum results in continuing population increase. This momentum will gradually taper off unless fertility rates rise again.

The U.S. total fertility rate is now about 2.1 children per woman because it blends together native-born fertility and the higher fertility rates of the immigrant sector.

The United States could stabilize its population at about 325 million by 2025 by maintaining a replacement level fertility rate of 2.1 for that entire period and reducing immigration to the replacement level, i.e., to about the same number as emigrate —leave— each year. An initial immigration moratorium of 100,000 annually for five years would help us overcome the momentum of the recent immigration surge. These steps would result in a stable population. We could then deal effectively with environmental problems which are primarily caused by relentless population growth and with our social and economic problems which are made much more difficult to solve because of ever-increasing numbers of people.

In summary, if replacement level fertility and zero net immigration were maintained for about 70 years (an average lifetime), the U.S. population would stabilize. But with continuing high levels of immigration, post-1970 immigrants and their descendants will account for a progressively larger share of the growth until, in the year 2050, they are projected to account for 90%, and growth will continue with no end in sight.