Why did everyone wear suits 100 years ago?

by BBG1976

It seems that every picture I see from around 100 years ago up until the WWII era the men are always in slacks, a button-up, and are wearing a tie. Was this really the epitome of casual wear for so long? When did it change?

BBG1976

So does a day without a reply mean it's being reviewed or just isn't worth a reply? If the latter, just let me know, I can take it.