'Hipster'

hipster is an old term, used endearingly to describe the young, hip, NY jazz crowd - read Kerouac for all the most pertinent usage.

This, from font of all knowledge, that is Wikipedia:

Hipster, as used in the 1940s, referred to aficionados of jazz, in particular modern jazz, which became popular in the early '40s. The hipster adopted the lifestyle of the jazz musician, including some or all of the following: manner of dress, slang terminology, use of cannabis and other drugs, relaxed attitude, sarcastic humor, self-imposed poverty, and relaxed sexual codes. Early hipsters were generally white youths adopting many of the ways of urban blacks of the time, but later hipsters often copied the early ones without knowing the origins of the culture.

Wasn't it Omelette Ertegun or Jerry Wexler who coined the term? Referring to, as you say, the appearance in the 40s of the white negro?
I'm gonna start ridin' in a Zoot suit with a 2 metre long gold chain... Now that, would be rad, dad...