Job gains are going to immigrants, and keeping young US-born men out of the workforce

Steven Camarota : Numbers of immigrants working up by 2.9 million , while U.S.-born Americans are not working.

He says it's hard to say what share of immigrants holding jobs are in the country illegally.

It's possible that half of the net increase in jobs went to illegal immigrants, he says.

But low-wage workers also create significant costs, he writes.