Its the Wall, of course, that is triggering these caravans. Its not hard to figure out that it is going to become much more difficult to cross illegally into the United States after the Wall is up.
So they are coming now.
Mexico's new Presidente has turned out to be a damned liar and is busy transporting central american immigrants north to the US border. There needs to be an answer to that. I don't see how you can completely close the border without hurting many US businesses but what else can you do with a hostile neighbor determined to flood your country with people?
Close the border. Scrap that trade agreement with Mexico and treat the hordes of illegal immigrants like an invading force meaning detain, process and return. Don't feel like paying $1 for an avocado? Well, consider it to be the price of sovereignty.