Whether anybody in the US is is irrelevant to whether data exists or used to exist from previous decades that was used to get an estimate of the average IQ of the US at that time in the past.
I was tested by the public school system of the second-largest city in Massachusetts and have no reason to believe that my experience was atypical.
About the same time as I was being tested,
in Diana v. State Board of Education (1970) a court ruled that a school could
not place students in a class for mild mental retardation because of a low
score on the Stanford Benet IQ test,
which of course implies that she was tested by her school.
There were other lawsuits like this in other US states.
I don't know what point you're trying to make. There isn't a national survey of IQ in the United States. There also aren't representative data sets from which you could model a national IQ of the United States (unless you think "people volunteering for the military" make up a strongly representative sample of Americans). And the United States is a gigantic industrialized country, exactly the kind of country where cross-sectional research projects like this sometimes do happen --- unlike most of the world, where the only reason people get IQ tests is because doctors suspect them of having cognitive abnormalities.
There is no such thing as "national IQ". That's all I came here to say. I didn't raise my hand and ask to litigate whether anybody on HN had ever taken an "official" IQ test. I'm sure several people have. Most of us: no.
The point of this thread isn't that IQ testing doesn't exist. It's that reliable (or even plausible) comparative national IQ metrics exist. That has to be true for the claim made upthread to make any sense. And: it isn't true.
