No, America should NOT build a wall to keep illegal Mexican immigrants out. It's very irrational. First of all, it will cost a LOT. I know that we're somehow planning to magically make Mexico pay for it, but how exactly is that going to work? Secondly, I really doubt it would be very effective. Walls, like fences, can be climbed over in the dead of night with the right tools. Sure, we could get security guards patrolling every square inch of it, but that seems like a waste of resources. And lastly, we have far more important things to worry about. Such as ISIS.
Yes it will cost a large amount of money, but it will open jobs up for US citizens. No one ever said Mexico will pay for it except Donald Trump, and we all know that guy is just flat out crazy. We could have drones circle around the border to catch anyone who is attempting to cross the border.
While it's true it may open up jobs for Americans, there are far more projects that are better worth out time that could also open up jobs, such as building safe houses for Syrian refugees. Our country already has a lot of debt, I don't think we should add to it just to build a wall that may or may not keep out illegal immigrants. And the drones are the same problem - too much money, not enough benefit. I also doubt that our people living near the border would enjoy having drones circling around their towns, and they would cost a lot to keep up and running.