Here's some of the walls being considered for the Mexican border

I personally like the 30 foot wall with razor spikes at the top. The risk of death climbing over that wall would be too great for even the bravest of souls.

 

Whatever wall has the solar panels on top, is my pick. Otherwise from left to right, number 4.

 

After that, all that's left to do is to ban all air traffic with Latin America. Job well done!

 

Don't forget Elon's tunnel boring machine. Can't let that fall into enemy hands.
All that being said.... I vote for the see-thru wall.
One more hit in the head by a 60# bag of drugs (launched from a catapult) whilst out on my midday stroll thru the barren deserts of Southern AZ... ... and I'll be shorting the S&P.
We are not on an island.
Surrounded by water.
Ocean water.

 

Tunnels as in under the ground tunnels? That's pure fantasy, they don't exist, impossible to build. Next you're going to suggest Mexican drug cartels will dig these "tunnels" under the border, lol, on what planet is that possible!

 

You put a bounty of 100 dollars a head for everyone caught crossing the border and there will be no crossing of the border in the open spaces. Then save the money for high tech on the tunnels, or more congested areas. Throw in a couple free tickets to the buffet at the local casino to keep bounty hunters motivated.