Trump is drunk off the Henney if he thinks Mexico would pay to build a wall, let alone think that would stop illegal immigrants from finding a way into the country. Not only that, him and followers forget that illegal immigrants are a key part of the American economy and take low-paying jobs that everyday Americans like you and me simply won't take. Construction is a big one. About 60% of Latin-American immigrants who come to America to work in that industry have a sophisticated understanding of the trade. They'll also be useful in filling future labor gaps as the baby boomers are retiring.
Not only that, it ignores a major part of the history of the country. People have literally been immigrating here since the birth of the nation, even before the conception of the country. I wonder how we forgot that America is a melting pot of cultures,languages,and ideas and not a homogeneous European nation.