I live in San Diego, which is largest city on the border and the busiest international crossing point in the world. I can take a lite rail to the border for $2.50 or walk/drive into Mexico at no cost. Each day there are 16 lanes of cars and thousands of people who walk north each day. Most head back south to be with families. I think there are at least 15 million northbound crossings a year.
The vast majority go back home... they just want to work. The folks who extend their visa are picking strawberries or processing meat in Greely or Alabama..
We should be debating a program that allows for a seasonal visa that allows our companies to thrive but also allows labor to return home.
In short' we have a wall along the entire border and the bad guys drive across trucks and the really desperate simply go over or under... 200p tunnels this year.