In 1939 what did they do?

Uh, a dime. If you're referring to purchasing power, it's a bit hard to say because so many things are so different today. A stamp cost 3¢, a newspaper was 2 or 3¢, a bus ride or a bottle of Coke...

S is a southbay ny mark. D is a denver mint.

Neville Chamberlain was Prime minister until may 1940 when Churchill took over.

The girls wre a LOT of high heels! And the dress style/paddern shown above.

In 1939 the same denominations circulated as we have today.