Yeah, and they compete for different jobs because the immigrants take jobs that otherwise would require higher pay to get workers to do.
People like to parrot Disney at this point but USCIS is closing that loophole.
Why? The law of comparative advantage says we get more productive when we have more trading partners, and the arrival of undocumented workers with limited English skills frees up low-skill American workers who can then specialize in tasks that require better English.
http://www.forbes.com/sites/artcarden/2015/08/28/how-do-ille...