This blending of Scots and Irish here in the USA is an interesting topic.

Behind it all is the ancient fact that the Highland Gaels were a people and culture imported to Scotland from Ireland. For centuries there was ongoing contact between the two. Young Highland pipers were sent to Ireland for training in their art. The English commented upon the Highlanders speaking "the Irish language".

Our modern notion of Scotland and Ireland being seperate political entities would have meant nothing to a 14th century Gael, who could have passed from the Highlands to Ireland speaking the same language and being within a shared culture.

Anyhow the muddling of the concepts of Scottishness and Irishness here in the USA has been helped along by the unfortunate term "Scotch-Irish". These Ulster Scots came here in an 18th century mass migration (c1717-1775).

But to many modern Americans the term "Scotch-Irish" is thought to mean people of mixed Scottish and Irish ancestry. Once I was out piping somewhere and a teenage girl came up and told me that her ancestors were from "Scotch-Ireland".