> From my vantage point, cutting off the drug cartels access to the US market could potentially do wonders to shifting the balance of power and helping Mexico in the long run.

If you think a wall is going to do this, I have a bridge in Brooklyn I want to sell you. A physical wall is going to slow the cartels down for a week while they round up a bunch of Mexican citizens at gunpoint and force them to dig tunnels into the US, build submersibles to get here via waterways, and just go buy a dozen ladders. There are literally people that can climb a 10 foot wall without a ladder.