By the way, I was probably oversimplified Bayard's comments. He simply meant that German fiddlers in Pennsylvania absorbed a great deal of Scottish / Irish music. When he studied the instrumental music of the region, he found those elements predominated among musicians of varied ethnic and cultural backgrounds. He did acknowledge stylistic elements and some tunes traceable to German forms and styles. To my knowledge he did not look at vocal music, so that's another area to look at.

That being said, I would argue that specically German influences in Pennsylvania remained regional and do not show up much in the wider American musical tradition. But maybe it's there and I'm too ignorant or tone-deaf to hear it.