Mexicans are not the only immigrant group. We often forget that. I recently met a girl from Eastern Europe who immigrated here. My friend's parents are immigrants from Greece. Immigrants do not only come from Mexico.
That's true. And every group had to face the same type opposition that Mexicans face today.
It used to be sociably acceptable for businesses to have signs reading: "No dogs or Irishmen allowed." At one time people complained about Italians ruining our neighborhoods or Poles destroying our culture or Jews threatening our sovereignty.
Today it just happens to be Mexicans..