Anyone know where the Clark Kent to Superman phone booth change legend came from?  I don't remember ever seeing him do that on the George Reeves TV show and very seldom in the comic books.  I wonder how that sterotype came to be?

1942

It's important to remember that most of the phone booths used when Clark Kent popped into one for the 1941 animation series, were larger and more private, built to be inconspicuous against - or into- walls, with only small glass windows (often with frosted glass).

The fact that they later used stand-alone phone booths with fully transparent glass walls for Superman to change in is of course one of those silly things that happen when people forget why he changed in phone booths. And what those phone booths looked like.

In fact, the only difference between the original phone booths he changed in and the storage closets he also sometimes used, was that phone booths were more accessible to the general public.

I remember Clark Kent changing into Superman behind a glass door  in the opening credits of the Fleischer Cartoons, but I don't recall if that was a storage closet or a phone booth.

A leftover, I suppose, from the early days when Superman WASN'T as fast as he later came to be -- when he could "outrace a speeding locomotive" but was not yet fast enough to be "invisible".

A lot of the Superman mythos falls under this heading. Much of what we think of as traditional is actually adapted and modified considerably from how the character started. Take Superman's powers, for a start. When introduced, he was from a "race of supermen" up there on Krypton, and everybody could do what Superman could do while still on his native planet. One thing they couldn't do, of course, was fly, which is why the rocket was needed to get baby Kal-El (or Kal-L to be historically correct) to Earth. But as Superman got more and more powerful, eventually being able to fly thru space with the greatest of ease (even returning to where Krypton used to be!), Kyrptonians got a serious downgrade, becoming mere humans when still on their homeworld.