https://clickamericana.com/topics/activities-fun/huge-outdoor-public-swimming-pools-1900s

What we white people gave up, rather than swim with Black people.

But John, we were also afraid of polio!

(a) Polio was endemic way before the 1950s.

(b) chlorine was known to deactivate the polio virus and had been in use since the turn of the century.