The plight of immigrants from Mexico.

A Immigrants from Mexico do far worse when they migrate to the United States than do immigrants from other countries. Those difficulties are more a reflection of U.S. immigration policy than they are of underlying cultural differences. The following facts from the 2000 U.S. Census reveal that Mexican immigrants do not move into mainstream American society as rapidly as do other immigrants.

1. Eighty percent of non-Mexican immigrants are fluent in English. Among Mexicans, the number is 49 percent.

2. Non-Mexican (working) immigrants have an average wage income of $21,000 a year. Mexican immigrants have an average wage income of $12,000 a year.

3. The typical non-Mexican immigrant has a high school diploma. The typical Mexican immigrant has less than an eighth-grade education.

4. Compared to other Hispanics, only 49 percent of Mexican immigrants are fluent in English, compared to 62 percent of non-Mexican Hispanics.

5. Mexican average incomes are about 75 percent that of other Hispanic immigrants, and Mexican immigrants have about two and a half fewer years of schooling.

Two other facts are worth noting. First, Mexican immigrants live in communities where 15 percent of the residents were also born in Mexico. Non-Mexican immigrants live in communities where fewer than 3 percent of the residents are from their native land. Second, Mexican immigrants account for a much higher proportion of the immigrant population than does any other group--29 percent in the 2000 census.

The last two points are key. Individuals become assimilated when their incentives to do so are great. An immigrant from Mexico who moves to East Los Angeles can survive knowing only Spanish and interacting primarily with people from her or his own community. A Bulgarian immigrant to Billings, Montana, must learn English quickly or return to Bulgaria.

A number of studies suggest that the most important factor in explaining English fluency and other aspects of assimilation is the proportion of individuals in one's community who come from his or her native land. When there are many, assimilation is slow; when there are few, assimilation is rapid. Mexicans often do poorly because they have been part of a large wave of immigrants who have similar cultures, languages, and backgrounds.

One other factor is that U.S. immigration policy selects immigrants from Mexico primarily on the basis of family connection rather than skill. Immigrants from other countries are more likely to enter and take jobs in highly skilled occupations. In fact, our most able immigrants come from North Africa--Morocco, Algeria, and Libya. Is this because those countries have the world's best educational systems and cultures? No, it is because it is virtually impossible to enter the United States from those countries. The only North Africans to get in are highly educated and talented.

Nothing inherent in Mexicans causes difficulties for them when they come to the United Stated. Instead, it is our immigration policy that encourages the formation of large, insular Mexican communities. Additionally, our policies do not employ the same selection criteria for Mexicans as they do for applicants from other countries.

Moving in the direction of skills-based immigration and away from relative-based immigration is one step we can take to ensure that immigrants do well and become integrated when they come to the United States. Moreover, a conscious policy that encourages a more balanced distribution of countries from which we draw immigrants will improve the speed of assimilation and raise the incomes of both immigrants and U.S. natives.

Edward P. Lazear is the Morris Arnold Cox Senior Fellow at the Hoover Institution and the Jack Steele Parker Professor of Human Resources, Management and Economics at Stanford University's Graduate School of Business.