During the 1980's, average wages for native-born workers hit a plateau, and those of recently arrived immigrants declined slightly.

It appears that employers are substituting new immigrant workers for young native-born workers.

At the same time, the number of native-born workers from ages 25 to 54 will not grow at all in the next two decades.

Nor are there notable differences between immigrants and native-born workers.

If properly designed, these changes could sharply reduce illegal immigration and would present no threat to the economic welfare of native-born workers.

"We cannot say with certainty that the growth of the foreign-born population has either hurt or helped native-born workers."

Immigrants do, of course, compete to some extent with native-born workers.

The study does not mean that native-born workers and long-term immigrants are not finding jobs.

Because of the disadvantages, finding native-born workers to fill such jobs can be a problem.

But even in those four job categories, native-born workers account for more than 40 percent of the work force.