45 percent of immigrants emigrate—either to return to their home country or to move to a third country (Jasso and Rosenzweig, 1990:124). Gross legal immigration numbers of about 800,000 per year, therefore, overstate the net effect of immigration.
Immigrants have a lesser or greater tendency to return to their home country, depending on where that is. Europeans have the highest rate of emigration, followed by those from the Western Hemisphere and from Asia. These numbers are of obvious importance for assessing the net immigration rates of people from these regions. The differences between gross and net immigration figures are generally greater for European countries than for Asian countries, for example, because of their higher emigration rates.
Using data from the 1990 decennial census and from the Current Population Survey in conjunction with demographic estimates of immigration and mortality, Census Bureau demographers Bashir Ahmed and Gregg Robinson (1996) suggest that emigration currently totals about 300,000 per year. Given about 800,000 legal immigrants a year, emigration claims about one-third of immigrants.17
The tension among policy goals becomes clear in examining the complex set of rules governing entry of legal immigrants. Current U.S. policy sets limits on both the overall number of immigrants and the number of immigrants in various categories. In pursuit of varying policy goals, however, these limits are tempered by exceptions. Categories are temporarily changed to accommodate new needs for humanitarian assistance, and new categories are introduced to allow for special cases. Given this complexity, it would be impossible to completely describe current policy in a few pages, so the following gives only its outlines—intended both to give a general idea of current policy and to illustrate its complexity.
Current U.S. immigration policy sets a flexible annual limit on the number of new legal immigrants, and then uses a complex preference system to decide which applicants will be given visas. The baseline annual limit now stands at 675,000 immigrants, down from 700,000 during the 1992-94 fiscal years. The annual
One specific use of emigration estimates is by the Social Security Administration, which must make assumptions about the proportion of immigrants who may depart from the United States. How many will not need retirement benefits? How many will be eligible for benefits? How many who are eligible will not apply? Answers to these questions cannot be lightly given because of their important fiscal repercussions. At the moment, the Social Security Administration assumes that about one-third of immigrants will emigrate and will not need retirement benefits (see Duleep, 1994, for a detailed discussion). Although this assumption appears to be consistent with the demographic estimates cited above, it may not accurately measure the demand emigrants will make on the system: many will have worked the required number of quarters to qualify for overseas payment of the retirement benefits.