Just as important, I'd add that about the time that hats stopped being fashionable, the suit, as the regular wear of men in most occupations most of the time, started to end.

I still find it odd to see old pictures from a century ago with everybody wearing jackets, vest and ties everywhere, even in some labor jobs (at least vests)!

e.g. hunters http://www.huntersgardenassociation.com/1900%20thru%201948.h...

miners http://japanfocus.org/data/j.miners.1900.gif

mechanics http://users.senet.com.au/~mitchell/lewis/cars/html/car1.htm

boxing http://www.archives.gov.on.ca/english/on-line-exhibits/sport...