Historically there are good reasons why women were not part of the "jazz on the road" culture of segregated America, I'm certain.   The element of the "cutting contest" with it overtones of males locking horns and adolescent ritual must have made it less of a female pursuit.

 Jazz musicians were often from a middle class or skilled background, even those from the ghetto, whereas their life on the road was more akin to the intinerant minstrel, the bottom of the social heap. Not the place for a respectable woman that the academic or conservatory musical path would be, was probably the attitude, though there was racism there as well.

There is also the matter of jazz instruments being mostly ones that all of society used to consider male. Are horns and drums jazz instruments because it is a male dominated genre or is jazz male dominated because horns and drums are more suited to jazz? In the early days I'd say both but more the former. In the last forty years the latter has possibly become a bigger issue.

This male dominance was definitely reinforced in a band bus culture. Since then, these social influences, with the "macho" playing elements, has become a part of the jazz tradition, unfortunatley.

 I think that these background social, race, and class issues are just as much a reason for the paucity of women in post bop and free jazz as the undemocratic nature of the actual music.

Free improv was borne of a different era and geography. I would think it is similar in gender split to classical music which is still extremely hierarchical IMO.

Good point about big bands Flattened fifth, I'm not sure that all girls find any instruments too macho it's more of a presumption that they will. "Which boys want to learn the tromobone?" I can imagine a teacher of my era asking, in front of a mixed class.

Yes, Calum...there are countless ones - thank the forces! I think my first listening experience was Melba Liston on trombone in Quincy Jones' band.

Of featured players, two of my favorites are Leni Stern, guitar (married to Mike) and Jane Ira Bloom of which her soprano on Art & Aviation is memorable (also features the Kennys: Wheeler and Werner).

Leni Stern's CD's from the late 80's: Closer To The Light (feat. a mellow David Sanborn) and Secrets (feat. the great one: Bob Berg) are recommended...