Illegal immigration is a securityproblem, and Trump is justifiably hammering that point home in the days leading up to the mid-terms. Legal immigration is an economic problem. Just how huge a problem is made clear by data released with the October jobs report. Immigrants, legal and illegal, accounted for more than half of working-age population growth over the past 12 months. The foreign-born working-age population grew 1.383 million, the U.S.-born rose 1.364 million. Nearly 5 million native-born were unemployed in October.