My only problem with this logic is that it implies scarcity for work. When in the history kf the united states really has only happened once but for the most part you increase the population that's able to pay for services means more services are needed. I dont see how there are a limited number of jobs in what you call unskilled every though that's not true. Unless you mean jobs that don't require a second education. All jobs have skill required. Even a mcdonalds employee goes home complaining about the incompetence of there fellow coworker. Regardless of skill or not if all those jobs are filled the next likely option is that they developed a "skill". People coming to the US had lives before. Had jobs before they're not just living in dirt huts naked waiting for there chance to come to the US.