Bruce Molsky regards old time music and part Irish & part African(the banjo is definitely African in origin). Although there are a many regional styles of fiddle playing and traditional dance in the US and Canada. New England tends to be (I think close to Scottish and Irish) and the Virginia and the (Round peak style) differs significantly from say Kentucky fiddling which tends to be cleaner and has less double stops and less cross tuning. Of course theres Cajun which is a mix on its own but part of it comes from the French Canadian tradition. French Canadian fiddle and dance music is derived oddly enough (according to Yvon Mimeault) from Scottish & and to some extent Irish music as opposed to French. (Although when french canadian fiddlers attended Fiddle tunes in Port Townsend (American Festival of Fiddle Tunes) encountered Mexican fiddle music they sensed something familiar maybe some latin roots. Then there is Texas swing which is probably the most recently evolved regional style. Also Mississippi Fred McDowell (blues player of course) said the blues originated from the reel (which originally came from scotland) although the blues are in 12bar phrases.

Anyway Im not an expert by any means on regional styles but I think that they are constantly evolving. For instance (I think purists may disagree) but any history of traditional Irish music must to some extent involve the Irish in America from Chief O'Neill the Chicago police chief who collected and published Irish tunes in the latter half of the 19th century. To Michael Coleman and Hugh Gillespie and James Morrison and many others who early recordings subsequently made their way back to Ireland. Which is why the sligo style (Colemans) became a lot more dominant. In that sense the Irish in America aided a revival of trad. music in Ireland where it was dying out (possibly thanks to the British and the church). Also many current top Irish fiddle players are second generation Irish Americans.

As Irish music and dance became popular people would have kitchen parties and bring a bit of money for some ham and booze. The church and govt. saw an opportunity to collect taxes on this and passed a law (The Church Hall Act?) requiring all dances to be held in halls (which were usually churches) and taxes could be collected.

I think the church influenced Irish step dancing to some extent too. Dancing was considered sinful anyway but at one time it involved using the whole body as there are remnants of Irish dancing in Newfoundland which uses the the whole body (as the substantial Irish population there was isolated for several hundred years.

As for other dancing styles take a look at clogging. Scottish Clog dancing is different from english which is different from southern clog dancing.

Irish set dancing which Im currently into, comes from the French quadrille (based on groups of two couples) which was brought back by the English during the Napoleonic wars and influenced Scottish country dance and American square dancing).

Anyway what was your question? cheers Petr/