It was apparently written by Irish musician Shaun O'Nolan and popularised by another Irish musician Mick Moloney. I don't see a source for the year and location of it's authoring. Maybe you could provide one?
And audiences in America isn't the same thing as American audiences. There was and still is a very large Irish diaspora in the United States. I'd also appreciate a source for the claim that it was intentionally written for American audiences.
No, it's an American song that tells an Irish perspective. It was written in America to be performed for American audiences.
Why do American audiences appreciate it?