If stopping illegal immigration is a goal, why won't a wall work? Humorous and popular series 'Adam Ruins Everything' looks at the logistics of building the wall. As it turns out around 40% of all undocumented immigrants in America came here by airplane and overstayed their visas.
Then there's the problem of circular flow. There are a lot of people that come to this country for temporary work and building a wall keeps them from going home. Additionally Mexico's economy is actually doing quite well now and that population growth is down.