sons are legal or illegal immigrants or whether they are nonimmigrants who are temporarily in the United States. In this report, we refer to either foreign-born persons or immigrants, unless we wish to distinguish a particular type of immigrant.

Impact of Immigration on the U.S. Population

What influence will immigration have on the size and composition of the U.S. population over the next half century?

To answer that question, the panel developed a demographic model that projected the population to the year 2050. This model projects an initial population under various assumptions about fertility, mortality, and international migration. It places special emphasis on understanding the effects of immigration on the total population, its age structure, the size of the foreign-born population, and the ethnicity of its descendants. The model adds a generational perspective to demographic projection by distinguishing immigrants and their descendants, along with the current native-born population, using data on fertility, mortality, exogamy (rates of intermarriage), and ethnic affiliation that vary by generation and ethnicity.

In our projections, we used five alternative assumptions about the numbers of immigrants in the coming decades: a continuation of the current number of net immigration, high and low immigration (a 50 percent increase and decrease from current levels), and two extremes—zero net immigration and twice the current rate.

If net immigration continues indefinitely at its current levels, there will be 387 million people in the United States in 2050, 124 million more than at present. Immigration will play the dominant role in that growth, accounting for 80 million, or two-thirds, of the increase. Even if net immigration were halved, to 410,000 a year, the population would still rise to 349 million. And if it were increased by half, to 1,230,000 a year, the population would be 426 million by the middle of the 21st century.

Immigration will also affect the age distribution of the resident population, with crucial implications for public policy. Under current immigration policy, enrollment in kindergarten through grade eight will increase to 53.7 million by 2050, 17 million more than the 36.8 million in 1995. If immigration were cut in half, that number would be 47.3 million; and if it were 50 percent higher, it would be 57.6 million. High school enrollments will rise from 14.0 million in 1995 to 20.3 million under the medium assumption about immigration—and to 2.5 million more or less than that under the high or low assumptions.

The U.S. population is aging: the number of persons aged 65 years and older is expected approximately to double between 1995 and 2050, no matter what immigration policies are adopted. With a low immigration assumption, the absolute size of the population aged 65 and over will be 73.0 million in 2050; with the

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