As I mentioned in an earlier thread, I've been reading a lot of Raymond Chandler novels lately (all of them, actually), and he mentions several historical American whiskies by name.

He also, however, repeatedly mentions how a bottle is "green label stuff" as though it were a designation of high quality. He applies this term to Old Forester and to Mt. Vernon Rye specifically and then uses it again to describe other, unnamed whiskies. I was curious if older bottles had a green label to denote a higher quality product or to designate BIB or something in the era following prohibition? Or is it just a figure of speech and if so, from whence does it come?

I know somebody will tell me . . . thanks in advance, dudes.