Several thorough studies have shown that any economic benefits of immigration are very small, and mainly go to the immigrants themselves. Immigration undermines the social, cultural, and ethnic cohesion necessary to sustain our society. These factors are more important than people think. We are losing our common language. Linguistic difference has destoyed or threatened to destroy several nations.
Many immigrants are openly disloyal to America.
Chinese immigrants are stealing our secrets and corrupting our political system. In the long run, it threatens civil war. We are losing our loyalty to a common heritage. Mexicans in Denver are protesting Columbus Day and treating Columbus as a villain. To any American, he is, by definition, a hero.