I just have to point out that in America, of all places, we're even having this conversation, about this "Problem." We have to use examples from Europe, where continental war, and real invasions are not just a reality, but pretty much their entire history.
But here, where we Europeans invaded, we need a wall to protect ourselves from having somebody to pay to mow our lawns. We have to write off the rest of the hemisphere as criminals, and drug dealers (Because we don't have criminals, and drug dealers, here in America, donchaknow?) to justify such an unAmerican stance.
America is immigration. Immigrants are America. The only "Problem" here is white people who don't want to share the wealth. If you want to stop Illegal immigration, than fund the people that make Legal immigration possible.