Bush has signed a bill that will create 700 miles of border fencing. Rather than focusing on the immigration and national security effects — you can find great arguments for and against fences elsewhere — I’d like to make the case it’s good for democracy.

Whatever you think the ideal rate of immigration is, a fence is good for it. As American citizens we have the right to decide how many immigrants we want (and from where, but that’s another story), and a fence helps us control and keep records on what’s going on. If you want more immigration, lobby for it and get a law passed. A fence, in and of itself, will do more good than harm because it enforces the rules decided through democracy.

Now, that’s not to say there are no credible arguments against a fence. Cost is always an issue with this kind of thing, for example. Also, there’s the question of how well it will work.

It is almost unquestionable that it will work to some degree. Illegal immigrants now tend to simply cross the border because it’s easiest. That avenue will be closed to them, so the act of illegal immigration will be, by definition, harder. That will decrease the number of attempts and increase the number of failures.

Some people I’ve argued with in person insist that, well, it might work for a few years, but what happens after five or 10? (My gut-level response is that folks south of the border won’t evolve wings that quickly, but I’m no biologist.) It’s certainly possible, even likely, that new systems of getting into the country will develop. Indeed, illegal immigrants from Asia often overstay visas as it is (I wrote about one for this story). But as I said, these systems are by definition more difficult than the ones they’re using now (otherwise, they’d be using the new systems now).

Robert VerBruggen blogs at http://robertsrationale.blogspot.com.