Yep, that'll stop them. It's not as if they can't walk down to the next cactus to come across.
If you extended the fence from sea to shining sea, and didn't add a bunch of patrols along its entire length, you'd probably see illegal immigration drop 25%. (Among other things, an unpatrolled fence invites people to cut holes in it.)
75% of a calamity is still a calamity.
There is no cheap, easy solution to illegal immigration, aside from:
1. Hiring a bunch of illegals to build a fence from sea to shining sea. (Sorry, you can't do a "cheap" fence at union scale rates.)
2. Drafting every able-bodied young American male for two years to patrol said fence. Pay 'em at the going rate for a US Army private.
3. Drafting every American woman of child-bearing age to have the next generation of border guards.
Just think: we'll need to make unauthorized infertility a court-martial offense.
The proposed 700 miles of barrier would cover nearly 40% of the entire border. It would require them to go literally hundreds of miles out of their way through some of the most forbidding terrain in North America. The rest would be monitored by sensors to track movement and initiate a response.
It's not a full 1,700 mile barrier, but it will reduce illegal border crossings a great deal.
Your thoughts, MI?