Considering the apparent danger (72 recently dead in a massacre in Mexico) and expense (~$5,000)  in migrating, it’s not surprising that the population of illegal immigrants in the US has declined.  From the Pew Hispanic Center report:

The annual inflow of unauthorized immigrants to the U.S. was nearly two-thirds smaller in the March 2007 to March 2009 period than it had been from March 2000 to March 2005, according to new estimates by the Pew Hispanic Center. This decline contributed to an overall 8% reduction in the unauthorized immigrant population, which fell to 11.1 million in 2009 from 12 million in 2007. By region of origin, the population of unauthorized immigrants from Latin American countries other than Mexico has declined most markedly. By U.S. region, the decrease in the unauthorized immigrant population has been especially notable along the nation’s Southeast coast and in its Mountain West.

This is significant demographically, and demographics are significant economically.  Without immigrants, the US population ages and declines much more rapidly.  An aging and declining population does not make for a sustainably growing economy.  Ask Japan.