Will there really be a wall? (Hint: Doubt it!) May be a fence... Of some kind... Perhaps buried sensors?... 2,000 mile shower curtain?... Or just something more economical? Do Not Cross Demagogue
As the security on the border has tightened the illegal population in the US has risen. Why? Because when people could come from Mexico for the harvest season and then return to Mexico easily, they would go back. Now they stay all year since it is more difficult to get to US in the first place.