I've been listening to some forties/big band music, and hearing the phrase "Eight To The Bar" come up a lot. There's the song, "Beat Me, Daddy, Eight To The Bar", the Chattanooga Choo-Choo will play its whistle eight to the bar when nearing Tennessee, and the Boogie-Woogie Bugle Boy plays eight to the bar.
I'm well aware what it means in terms of music,
(I'm sure someone will skp the More Inside and post an explanation of this anyway) -- what I want to know is, how did the phrase come to be in common usage, to symbolise, what, hipness, coolness, maybe blackness?
It's as if words like "shredding" for fast guitar playing, or "cross-fading" for what DJs do with their decks became commonplace terms. It's a reasonable obscure technical term. How did it make it into broader cultural usage -- and did it extend further? Did people say "I love your hat, it's so eight-to-the-bar"?