Before desegregation in the 1960s, men and boys in most states as well as all YMCAs went swimming nude. Desegregation was in race (whites & blacks), but also gender (outside of bathrooms and dressing areas). Then concept of modern swimwear is to wear the minimum fabric needed to cover the genitals - to minimize negative impact on sanitation and swimming performance. This would be Speedo briefs or very short swim trunks for men and bikinis for Women. Then synthetic fabrics started becoming more readily available, reducing the negative sanitation impact of wearing more fabric in swimming pools, so modesty has a little more influence in swimwear, but not much. Skintight one-pieces are for women who wanted a tiny bit of modesty, boardshorts for men. Speedo briefs got some bad stigma in America due to classical / associative conditioning from their abuse in the gay movement, so the norm for men is medium-length swim trunks or boardshorts (skintight jammers for competitive swimmers that