tion helps to bear the burden of the preexisting public debt through tax payments to cover interest or repayment charges.2

Much like anyone else in the population, immigrants use services that are costly to provide, or that others can use less freely—so-called congestion costs. Examples include services from roads, sewers, police and fire departments, libraries, airports, and foreign embassies. These services may have a public good aspect, but because they are highly congestible, we treat them as if immigrants raise both the demand for them and the cost of meeting that demand, in proportion to their numbers. Such items have both a capital cost and a current cost, and we account for these separately.

Additional members of the population, whether immigrant or not, crowd the existing social infrastructure, including roads, libraries, airports, sewage and water supply systems, and public buildings. We include in our analysis a cost of investment for each incremental immigrant to replicate the existing social capital stock. We have done this in two ways. First, when we include the present value of a per capita share of government expenditures on congestible goods and services, we implicitly include this capital cost because capital outlays are an item in such expenditures. Second, we use a direct estimate of the per capita value of net public capital (U.S. Department of Commerce, 1994), and use an annual flow of services plus depreciation of this capital, while omitting the capital outlays from expenditures on congestibles.3 These two methods yield nearly identical results.

Sensitivity of Fiscal Impacts to Immigrant Characteristics

Apart from their simple numbers, the specific characteristics of immigrants influence their fiscal impacts. Immigrants arrive with human resources different from those of the rest of the population. In recent years, for instance, there has been concern that immigrants are disproportionately poor and uneducated. Such immigrants may both pay less in taxes and receive more in benefits than natives do. An immigrant's age at arrival is also important. Natives begin life in the United States when they are born, but an immigrant can arrive at any age; the modal age is around 25. If she arrives after school age, although she may have less education than natives, the public costs of her education have been borne by the sending country. Although she may give birth to children in the United States


Just as a larger population helps dilute the costs of past obligations, it also dilutes the per capita value of publicly owned wealth of various kinds (national parks and forests and publicly owned mineral rights, for example). The calculations below do not include such effects.


The estimate of total net public capital is taken from Survey of Current Business (1994). The annual flow is obtained by multiplying the per capita value, $17,000, by the assumed rate of interest plus a rate of depreciation of 4 percent. The descendants of the immigrant are also taken into account, and a net present value is then calculated.

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