There is a simple solution to all this. Close the border. Set up asylum seeking centers inside Mexico.
Mexico is obviously unable and unwilling to control their northern border; the towns where the illegals try to cross are held by cartels with not a federale in sight. Should be a piece of cake to set up a few centers - after we do Mexico a favor and blow a few hundred local cartel members away.
Um, the cartels and the representative government in Mehico are connected at the genitals.