You can't be serious. American history did not start in 1980. The vast majority of the US population throughout its history has been European-descended.
Maybe all non-European immigrants were only brought in as workers (and also slaves), so your argument may be right.
Let me rephrase then: The US has always been an immigration destination, so it's interesting that some immigrants are seen as different enough to be singled out. Spanish-speaking immigrants and Chinese arrived in US america much earlier than the famous NY around the turn of 20th century ships from Europe with Italians, Germans, Irish, Russians did.
I don't have numbers to cite, so I'll stop arguing more :).
I don't either, but you did say "Caucasian-looking"...
A mass migration from any foreign culture (that is, highly different from the host culture) would be treated with alarm by the locals anywhere, in any country. It's not a phenomenon specific to the US. The US just happens to provide a particular historical instance of it. Vancouver seems to be providing us another.