We don't have an immigration problem, as I understand it. What we have is a tax evasion problem. Too many U.S. employers are willing to break the law by not withholding and paying the employment taxes associated with those that they hire.
The answer is not in the building of fences, because the problem is not that people are crossing the borders. The problem is with our own citizens and employers in building a culture in which it is acceptable to not pay taxes. And the problem is with the misallocation of resources.
When we apply the resources to fix the real problem, and when we clean up our culture of crime, we can improve the situation. Until then, we are just serving pork.