That's one of the problems. Actually securing the southern border is a huge task. Once you start talking about the northern one, it just seems practically unrealistic to me and frightening as well. If you've ever been to Boundary Waters, Minnesota, imagine what it would take to do that there, and then multiply that by 1,000.
I'm sympathetic to border security being a legitimate cause. I just think we have to consider what kind of government it would take to do that in a nation with borders like ours, and whether that's the kind of government we want. I definitely don't support laws against employing illegal immigrants or renting rooms to them. And I'm not a fan of the wall approach either. I'd rather just ease up on legal immigration to the point that hardly anyone has an incentive to do it illegally, and reserve our right to deport or prevent entry of terrorists, fugitives from the law, and people with certain contagious diseases. We'll never be able to keep them all out, which is part of what the 2nd amendment is for.