'We are a nation of immigrants' The backing of the media and the nation's largest political party gives the statement enough credence so a lot of people won't think about it, but it is seriously flawed on many levels.
First there is a little sleight of hand because we are not a nation of immigrants. Many of us do have immigrant parents or grandparents or perhaps further back,
I can't agree that it is "slight of hand." Instead, the idea is that our nation is made up of immigrants or the "children of" immigrants -- meaning that our ancestors were immigrants to this country. And, outside of those that are primarily of Native American descent, this is true.
but then also they were legal immigrants in most cases.
And this is "sleight of hand" -- since for pretty much all immigrants who came to the US, "legal immigrant" has little real meaning, since there were basically no qualifications for Europeans who immigrated to the US; nor was their any type of mechanism set up to find, much less, remove anyone who wasn't a "legal immigrant." Once they were in the country they were basically "legal" by default.
Why do we have restrictions on immigrants now when they didn't exist in the past? When didn't they?
So a few got through in the distant past without meeting various requirements, not an obvious and convincing argument anymore.
But it gets worse. The argument is claimed to be A-priori, based on simple logic and not requiring data to support it. It could support immigration of 900,000 a year as at present or an unlimited number as a number of the more socialist European countries have decided.
And the simplest explanation for our restrictions today are "racism." We had no issue letting in "people like us" -- up until the 1920s, and beyond, the only real restrictions actually created tended to be 1) Not Chinese and 2) that the people were not immoral (prostitutes and convicts were banned in 1875 -- and more morality prohibitions were created over the years).
In the 1920's, the Chinese prohibition was lifted but, in exchange, we saw the first quote systems. Of course, those quotas basically allowed anyone who showed up from Europe, while placing severe limits on Chinese, Japanese, and other "not like us" countries. Over the last century we've progressively become more restrictive with immigration but we've largely retained the bias that allows someone from a European country to immigrate, and much harder for individuals from other parts of the world.