Okay America,
We had the Berlin Wall, which divided a densely populated city in half. It had mines, extensive and ruthless border patrol. And guess what? People still got around this.
If you seriously think an unmanned (or sparsely manned) wall between countries, in which you can buy Visas to fly over it will do anything at all, you're dumb as forget.
To me it sounds like SeventhSandwich is just about the only one here who is actually capable of adding some insightful opinions