From the article in undertakeress's''ss's link

When immigrants don't have jobs, they don't stick around, said Dawn McLaren, a research economist at Arizona State University who specializes in illegal immigration.

Anyone who says that hasn't driven up and down Cooper Street in Arlington, Texas anytime in the past several years. Just yesterday there were 4 separate packs of Mexicans (almost certainly illegal) with at least 15 in each group, all waiting for that "work today, paid today" job.