“There is good evidence that after the raids the number of native-born workers increased significantly,” Kammer writes, noting that all of the plants were back to full production within five months. “But Swift would not provide information on how its workforce has changed. Swift also has recruited a large number of refugees who are legal immigrants.

“At the four facilities for which we were able to obtain information, wages and bonuses rose on average 8 percent with the departure of illegal immigrants.”