Don't Fence Me In

You can erect as many fences as you like, the Mexicans are not going to stop coming until their own country gives them a better break, or until there are no more opportunities for them here. That is, when the people that employ them here pay higher salaries to Americans to do the same jobs they won't do now for cheap. Or when somehow and at long last, the standard of living in Mexico rises for the poor.
In either case, please don't hold your breath. Until these very long term issues are dealt with in a less cosmetic, obnoxious, obviously vote-seeking manner than a wall, the Mexicans will continue sneaking in. You build a wall, they will find ways to get through it. They are nothing if not committed.
Now, the wall is not a bright idea but I do think that if people want immigrants to stop coming, the laws need to be enforced better. And enforcement needs to happen on both sides. On the Mexico side, nobody ever stops anyone from crossing; if anything they probably give them their box lunch and send them happily on their way. After all, they are the second source of national revenue after oil sales.
Instead of making broad and stupid gestures like a wall (but what do you expext from Bush), the US should be sitting very seriously at the table with the Mexican government and reading it the riot act. It takes two to tango, and so far it seems to me that the immigrants get penalized, while the fat cats on the other side of the border who allow this situation to thrive get away with it.