Slavery, indentured servants, illegal immigrants,....
America's economic engine has always needed low cost labor. None of the above are very good ways to fill this need.
Our need for labor is not sufficient cause to allow all the problems associated with illegal immigration.
As I've stated before on these threads: the HS and college kids I know need and want PT work (some of the college kids will work FT and go to school FT -- that's a heck of a work ethic).
These kids tell me illegals aleardy have the jobs the kids would ordinarily do.