If these individuals also have wives and children, then your problem is bigger. In any case reach the United States and offered to work looking for a salary enough to survive, displacing people born in the U.S., causing a problem of unemployment because some prefer to hire cheap labor. (illegal worker)

When illegal worker receives his salary, an amount of money sent to their country of origin for your family, with that money that should recirculate within the U.S. does not occur, causing bottlenecks in the U.S. economy.

This is evidenced by the huge remittances of money coming to Peru for these immigrants (legal and illegal) who seek to keep his family financially. The money should stay in the U.S. to be recirculated to other parts, affecting the U.S. economic model.

With a big tax to such shipments, a ban on hiring immigrants with family outside the U.S., dismissal for workers who make these items, fining employers who hire these workers, etc., this could achieve a increase in consumption and domestic savings in the U.S.

Wanting to improve the U.S. economy without stopping these irregularities, it is like trying to fill a pool with a hole in the bottom ...

http://www.usillegalaliens.com/impacts_o..._jobs.html
http://www.cis.org/node/759