This entire concept is LUDICROUS!More than half of all illegal immigrants come into our country by plane. We have a nation divided, a totally uncertain health care system, a sub standard educational system, increasing distrust between law enforcement and the citizenry, and a breakdown of trust between the American people and their elected officials. We have children starving, without education, and people without basic healthcare. Spend the $21 billion on them! If you feel the need to make draconian cuts to Medicaid, then a border wall is an unnecessary extravagance! Please stop pandering to this mentally unstable person voted into office by an electoral college procedure that is long past its expiration date and let's get back to working FOR the country and not against the entire rest of the world.