Conclusions and Implications 5. The results of the study make clear the importance of return migration, the length of time immigrants stay in this country, and the differences between returnees and long-term settlers in considering immigration's social and economic effects. The purpose of the study was not to estimate the public costs associated with immigration, but the results demonstrate that cost effects should not be estimated solely on the basis of the total number of immigrants in the country at a fixed point in time. Length of stay in the United States and the characteristics of those who stay for long periods of time should also be taken into account. In the study sample, about 50 percent return to Mexico after only two years, and by 10 years, almost 70 percent of those who came to the United States have returned.
Return migration is even more pronounced for undocumented immigrants.
Close to 40 percent of those in the sample return to Mexico after only one year in the United States. Those who do stay for five years or more are the most educated and have the strongest ties to the labor market. For these reasons, they are also the immigrants more likely to be assimilated into the state and national economy and less likely to impose public costs. The remainder of this chapter suggests the relevance of the findings in considering these issues. In this section, we use the probabilities of returning to Mexico that are derived from the life tables in Chapter 4 to forecast the number of immigrants from western Mexico who would remain in the United States continuously for longer than 10 years.