According to my research males were once REQUIRED to swim in the nude at public pools.
The American Public Health Association mandated nude swimming from 1926 until 1962, and thousands of high schools around the country enforced the tradition.
The first recreational indoor pool in America was a YMCA in Brooklyn New York in 1885. Because swimsuits back then were made of wool, and their fibers would clog the pool’s relatively filtration systems, nude swimming was enforced.
By the 1920s, there were other, more comfortable swimming alternatives but the naked swimming continued.
In 1922, The Sanitation of Bath Houses by William Paul Gerhard, explained that nude swimming is encouraged alongside a pre-swim
Gerhard wrote nearly 100 years ago,
“Much can be done to keep the water in a swimming pool sanitary by an efficient supervision and management of the bathers.
A physical examination of the bathers, while nude, to exclude the diseased, accomplishes much good, but it is difficult to enforce, except in YMCA buildings and in school or military baths.”
For 50+ years no one really seemed to question the nudity rule. For males anyway. Girls were required to wear bathing suits.
But provincial attitudes started to prevail in the early 1960s. Parents started complaining and in 1961, in Menasha, Wisconsin, high school boys and their parents petitioned the school board to allow boys to wear swim trunks to swim practice.
A prudish mother said at the meeting,
“The boys were affected morally, physically and psychologically by forcing them to swim in the nude.”
But the petition was voted down. The (all-male) board claimed swim trunks would be prohibitively expensive and that swimming nude would also build a man’s character.
The board’s director said,
“Physical education considers that this experience is a good one for later life, for example the armed services, where the disregard for privacy is real and serious.”
The YMCA had no national mandate, so each location had it’s own rules about MALE nude swimming.
The tide supposedly began to shift in 1961 when Ervin Baugher, the general secretary of the Allentown, Pennsylvania, YMCA said the only rational reason to continue the tradition of nude swimming was
“encouraging a proper attitude toward the body.”
By the mid-70s, nude swimming was being phased out. (Probably by the evil swimsuit industry!)
The nude swimming tradition is the basis for several YouTube docs, like the one below one. The narrator says in one,
“Our society has so sexualized nudity, particularly child nudity, that we can’t conceive of a time when kids went naked without any sexual implications.”
As a gay man, who grew up in the 70s in Texas all I can say of this phenomenon is, I was born at the wrong time, although neither my junior high or high school had a pool.