Was there really an all-boys-must-swim-nude rule enforced in school and YMCA pools during the late 50s until the early 70s in the US?

I was told that such a policy existed, by someone a fair bit older than me.
At first, I thought he was pulling my leg. But when I looked it up, it appears that such a thing was commonplace in the US back in the 50s to early 70s. It appears that my source wasn't just pulling the wool over my eyes - there really was such a policy.

It obviously caught me by surprise, considering the US of A is the land where a pop starlet's "accidental" nipple exposure from a wardrobe malfunction ends up becoming a towering monument in the pop-cultural landscape, and the words "puritanical" and "America" often go hand-in-hand when the country is discussed from a (usually) European perspective.

Was the cultural/moral zeitgeist of the time so very different from now that it was widely considered to be perfectly normal for adolescent boys and adult men to abide by a rule that required them to swim nude in school and YMCA pools?

My source also told me that it was perfectly normal for the Agony Aunts of the time to advise mothers of teenage boys to have their sons swim naked, so that their daughters could "get a better understanding of the male body".

I've come across articles that claim this, although I cannot verify as to the validity and veracity of these claims.

Or, is this whole thing just a cleverly made-up hoax, like the many stories of Bigfoot and Elvis sightings that abound in the tabloids?
This is a swimming pool.
This is a swimming pool.
Was there really an all-boys-must-swim-nude rule enforced in school and YMCA pools during the late 50s until the early 70s in the US?
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