The number that I remember was 30%...

...in that about 1/3 of the population was for the revolution, about 1/3 was decidedly against it, and the other 1/3 were basically don't care, leave me the hell alone types.

The current 3 way split is not new in any sense. It's always been there. What has changed is that the 1/3 who just want to be left alone no longer have the frontier to flee to. The polarization we see, really isn't a 50/50 split and never has been. That narrative sells more papers and generates more clicks.

As for the citizenship test? The number of non recent immigrants who could pass it is pathetically small. It should be a requirement to get a High School diploma that students pass that. It's a pretty easy test for anyone who didn't sleep through American history.

The fact is that immigrants are usually the most patriotic in a truer sense because they chose to come here and work to become citizens. Far too many who were born here are infected with the malaise about it all you describe. What we end up with are political rallies that are about as substantive as local High School pep rallies before this weekend's game.