Why Not Legally?
Roughly 11 million immigrants inhabit the United States. On the positive, illegall immigrants have raised the wealth of America by less than 1%. To contradict that, is that tiny percentage really worth letting the American workers, who pay taxes unlike illegal aliens, lose positions in jobs to those who don't pay taxes and takes a smaller paycheck. Also, illegal aliens who use utilites, such as schools, sucks funds from government spending like a drain because of their not paying income taxes.
Of course, there are issues such as documentation running out and immigrants being deported before they are able to renew them, but the issue where immigrants stay in our country without the intention to renew, or even obtain documentation, has to be stopped. The United States' Naturalization process is one of the easiest in the world, taking the effort to become legal makes everything easier and less stressful for everyone in the end.