In the 50s, the industry standard for measurements was a 10in (25cm) difference between the bust and waist. Which means if your bust is 36in, your waist measurement is 26in - hmmm, not so for women these days I think. In the 50s, girls as young as 15 started wearing girdles or waist cinchers (not shapewear - not enough support) so their waists were trained into shape - comfy!
|Girdle front - source-|
|Girdle back -source-|
|Long line bra - source-|
Also further to my last post on slip dresses, the VFG also has a great post on Slips. I'll update my last post with this link also.