I have several ancestors with very common Irish names (ex: Patrick Sullivan, Daniel McCarthy) that came to the US in the 1800's. I even have wives married names in several cases, but their wives first names are common too (ex: Mary, Margaret).

I have census records that list that they were born in Ireland, and I know that they lived in Massachusetts when they came here. But I don't know where in Ireland they are from, and the common names mean that any searches turn up too many to be able to determine which ones are my relatives.

Has anyone else faced this problem and been able to solve it? Any suggestions of how to determine county or town of origin for Irish immigrants with common names?