In the following decade, the suit changed a great deal. World War II meant that everything had to be rationed, and so there was no more fabric for these elaborate full-cut large suits. Instead, the 1940's suit was characterized by minimalism. The grey flannel suit became the option of choice for professional everyday wear. It wasn’t double-breasted, but rather single-breasted, and it had narrow lapels and a very trim-cut trouser without cuffs, in order to save fabric.
For the same reasons, waistcoats or vests became unpopular. If you look at the suit from the 1940's, it is very close to the fashion of a 2020 suit, because it’s lean, trim, and overall, very slim. Of course, the fabrics were still a lot heavier than they are today and they also had a bit more texture than what you would get today.
The exception in the 1940's minimal suit was the rebellious Zoot suit. It was a product of the counterculture rebellion youth, particularly in African American and Mexican communities. They had baggy pants, a long jacket, and everything was oversized and excessive. The shoulders were super padded and often, people criticized it as being unpatriotic because it put your own idea of fashion beyond the rationing of fabric.
Click the 1950's