Anyone interested in the Scots-Irish in America should read David Hackett Fischer's Albion's Seed. James Webb's Born Fighting: How the Scots-Irish Shaped America has been one of my wife's favorite books. Another that we both enjoyed is Grady McWhiney's Cracker Culture: Celtic Ways in the Old South. Another title that should be helpful is James G. Leyburn's The Scots-Irish: A Social History.

I also recommend Partisans and Redcoats: The Southern Conflict That Turned the Tide of the American Revolution by Walter Edgar. Anyone wanting to fast-track themselves into a history of the Scots-Irish and their influence on the Revolution (America's First Civil War) should start here.