3 button vs. 2 button

[MisterGrey]

Then why were suits so commonly vested? I would think eliminating the vest would reduce cost more.

How many vested suits of the 30s were holdovers from the 20s, though? The history course I took two years ago actually delved into the culture of the various time periods we studied, as opposed to strictly the politics; one of the tidbits I found interesting was the assertion that three piece suits saw a decline in manufacture during the depression because of the amount of material required, and that it became fashionable to wear a sweater or sweater vest with one's suit, because of the simplicity of knitting one (as opposed to the work gone into a proper suit vest, with buttons and lining and etc).