The issue of building a wall is more than about immigration its also about drugs. I dont get where you say MOST come in through Visa overstays that number is around 40%. Still a high number but not MOST. The overland trade is favored by Cartels and Smugglers (the human trafficking industry is very profitable), providing yet more $$ for cartels that hang people from bridges and chop up tourists and locals continuing the instability of Mexico. Go look up the human trafficking trade, Mothers regularly put their daughters on birth control before crossing because they are regularly gang raped by Coyotes. Ranchers in Texas/New Mexico/Arizona regularly find dead bodies and clothing of young girls on trees as markers. The amount of drugs brought into this country illegally via the southern border is ridiculous. Almost 1.6million kilograms in 2009 alone. The average body weight of an amerifat is 80 kilos. Btw that number is JUST WHAT WE SEIZED. I dont get how you people can argue for an open southern border.
https://www.justice.gov/archive/ndic/pubs38/38661/movement.htm