My relatives called "Horrigan", "Horgan" and also "Harrigan" are from Killorglin, County Kerry.
The folks who do the Irish county websites have info about some 1911 census that might be interesting for you. All of my relatives left before that. I think this is their URL:firstname.lastname@example.org
There is also irl-cork, and probably other Irish counties...but ask for help from these folks, they are active in geneology and want to assist you!!!
All the best,