Linda is right; America needs unskilled workers to do the jobs that lazy Americans won't do themselves. These unskilled people have more character, drive, and integrity than any American. In fact, they are morally superior in every way. Thus, if we don't bring in such people and provide their cheap labor to companies, a huge chunk of work will be left undone in America.
Take the fast-food industry. Can one image the chaos that would ensue if American teenagers were recruited for such work? No American teenager would ever consider such a job, so the positions must be filled by unskilled people who come across the border. And since lazy Americans all benefit, it is only fitting that they deal with the resulting social costs.