"And FYI, chicago has strict gun laws, the surrounding states don't; maybe they too need a wall?"

But, but.....Chicago has strict laws  .....doesn't that mean they will be obeyed? No? You mean - the bad guys will always get guns somewhere else, legal or not? Who would have thought that? But give them a "law" that says "no guns for you" - now THAT will stop them dead in their tracks.