The unemployment rate is low because there are a lot of jobs, not because people aren’t looking for work. Since President Bush was first elected roughly 5 million people have reentered the work force. Since his tax cuts of 2003 were fully implemented, 2.3 million new workers have entered the labor markets. Both new job seekers and over a million previous job seekers have been absorbed. BuzzCharts: Jerry Bowyer on the April 2005 Jobs Report on NRO Financial
Of course, there's a number missing: how many of these newly employed people are Americans? If the majority of them are immigrants, then it benefits the Mexican economy more than it does the American economy.
And when you speak of new entries in the labor market, how many of them "entered" via the Rio Grande?