Hair Further's promise to build a border wall at Mexico's expense is laughable, if it were not made by the chief executive of a waning superpower. This chart shows that detected illegal border crossing have declined significantly. A wall will not stop determined immigrants or invaders--history has repeatedly demonstrated that. His folly is only effective as a public relations ploy intended to rallying his nativist base around one of their bête noirs, immigration. They fail to realize that up until 1924 the United States had no immigration quotas (except for the Chinese hordes building the westward railroad expansion). All an immigrant had to do was show up at Ellis Island, and if he was literate in his own language, he was admitted. 'Merica was built on the backs of immigrants. The last majority northern European "white" immigrant population was way back in 1840s.